linux/lib/Kconfig.ubsan

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# SPDX-License-Identifier: GPL-2.0-only
UBSAN: run-time undefined behavior sanity checker UBSAN uses compile-time instrumentation to catch undefined behavior (UB). Compiler inserts code that perform certain kinds of checks before operations that could cause UB. If check fails (i.e. UB detected) __ubsan_handle_* function called to print error message. So the most of the work is done by compiler. This patch just implements ubsan handlers printing errors. GCC has this capability since 4.9.x [1] (see -fsanitize=undefined option and its suboptions). However GCC 5.x has more checkers implemented [2]. Article [3] has a bit more details about UBSAN in the GCC. [1] - https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html [2] - https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html [3] - http://developerblog.redhat.com/2014/10/16/gcc-undefined-behavior-sanitizer-ubsan/ Issues which UBSAN has found thus far are: Found bugs: * out-of-bounds access - 97840cb67ff5 ("netfilter: nfnetlink: fix insufficient validation in nfnetlink_bind") undefined shifts: * d48458d4a768 ("jbd2: use a better hash function for the revoke table") * 10632008b9e1 ("clockevents: Prevent shift out of bounds") * 'x << -1' shift in ext4 - http://lkml.kernel.org/r/<5444EF21.8020501@samsung.com> * undefined rol32(0) - http://lkml.kernel.org/r/<1449198241-20654-1-git-send-email-sasha.levin@oracle.com> * undefined dirty_ratelimit calculation - http://lkml.kernel.org/r/<566594E2.3050306@odin.com> * undefined roundown_pow_of_two(0) - http://lkml.kernel.org/r/<1449156616-11474-1-git-send-email-sasha.levin@oracle.com> * [WONTFIX] undefined shift in __bpf_prog_run - http://lkml.kernel.org/r/<CACT4Y+ZxoR3UjLgcNdUm4fECLMx2VdtfrENMtRRCdgHB2n0bJA@mail.gmail.com> WONTFIX here because it should be fixed in bpf program, not in kernel. signed overflows: * 32a8df4e0b33f ("sched: Fix odd values in effective_load() calculations") * mul overflow in ntp - http://lkml.kernel.org/r/<1449175608-1146-1-git-send-email-sasha.levin@oracle.com> * incorrect conversion into rtc_time in rtc_time64_to_tm() - http://lkml.kernel.org/r/<1449187944-11730-1-git-send-email-sasha.levin@oracle.com> * unvalidated timespec in io_getevents() - http://lkml.kernel.org/r/<CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@mail.gmail.com> * [NOTABUG] signed overflow in ktime_add_safe() - http://lkml.kernel.org/r/<CACT4Y+aJ4muRnWxsUe1CMnA6P8nooO33kwG-c8YZg=0Xc8rJqw@mail.gmail.com> [akpm@linux-foundation.org: fix unused local warning] [akpm@linux-foundation.org: fix __int128 build woes] Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Marek <mmarek@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Yury Gribov <y.gribov@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 23:00:55 +00:00
config ARCH_HAS_UBSAN_SANITIZE_ALL
bool
ubsan: split "bounds" checker from other options In order to do kernel builds with the bounds checker individually available, introduce CONFIG_UBSAN_BOUNDS, with the remaining options under CONFIG_UBSAN_MISC. For example, using this, we can start to expand the coverage syzkaller is providing. Right now, all of UBSan is disabled for syzbot builds because taken as a whole, it is too noisy. This will let us focus on one feature at a time. For the bounds checker specifically, this provides a mechanism to eliminate an entire class of array overflows with close to zero performance overhead (I cannot measure a difference). In my (mostly) defconfig, enabling bounds checking adds ~4200 checks to the kernel. Performance changes are in the noise, likely due to the branch predictors optimizing for the non-fail path. Some notes on the bounds checker: - it does not instrument {mem,str}*()-family functions, it only instruments direct indexed accesses (e.g. "foo[i]"). Dealing with the {mem,str}*()-family functions is a work-in-progress around CONFIG_FORTIFY_SOURCE[1]. - it ignores flexible array members, including the very old single byte (e.g. "int foo[1];") declarations. (Note that GCC's implementation appears to ignore _all_ trailing arrays, but Clang only ignores empty, 0, and 1 byte arrays[2].) [1] https://github.com/KSPP/linux/issues/6 [2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92589 Suggested-by: Elena Petrova <lenaptr@google.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Dmitry Vyukov <dvyukov@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com> Link: http://lkml.kernel.org/r/20200227193516.32566-3-keescook@chromium.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 03:12:31 +00:00
menuconfig UBSAN
UBSAN: run-time undefined behavior sanity checker UBSAN uses compile-time instrumentation to catch undefined behavior (UB). Compiler inserts code that perform certain kinds of checks before operations that could cause UB. If check fails (i.e. UB detected) __ubsan_handle_* function called to print error message. So the most of the work is done by compiler. This patch just implements ubsan handlers printing errors. GCC has this capability since 4.9.x [1] (see -fsanitize=undefined option and its suboptions). However GCC 5.x has more checkers implemented [2]. Article [3] has a bit more details about UBSAN in the GCC. [1] - https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html [2] - https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html [3] - http://developerblog.redhat.com/2014/10/16/gcc-undefined-behavior-sanitizer-ubsan/ Issues which UBSAN has found thus far are: Found bugs: * out-of-bounds access - 97840cb67ff5 ("netfilter: nfnetlink: fix insufficient validation in nfnetlink_bind") undefined shifts: * d48458d4a768 ("jbd2: use a better hash function for the revoke table") * 10632008b9e1 ("clockevents: Prevent shift out of bounds") * 'x << -1' shift in ext4 - http://lkml.kernel.org/r/<5444EF21.8020501@samsung.com> * undefined rol32(0) - http://lkml.kernel.org/r/<1449198241-20654-1-git-send-email-sasha.levin@oracle.com> * undefined dirty_ratelimit calculation - http://lkml.kernel.org/r/<566594E2.3050306@odin.com> * undefined roundown_pow_of_two(0) - http://lkml.kernel.org/r/<1449156616-11474-1-git-send-email-sasha.levin@oracle.com> * [WONTFIX] undefined shift in __bpf_prog_run - http://lkml.kernel.org/r/<CACT4Y+ZxoR3UjLgcNdUm4fECLMx2VdtfrENMtRRCdgHB2n0bJA@mail.gmail.com> WONTFIX here because it should be fixed in bpf program, not in kernel. signed overflows: * 32a8df4e0b33f ("sched: Fix odd values in effective_load() calculations") * mul overflow in ntp - http://lkml.kernel.org/r/<1449175608-1146-1-git-send-email-sasha.levin@oracle.com> * incorrect conversion into rtc_time in rtc_time64_to_tm() - http://lkml.kernel.org/r/<1449187944-11730-1-git-send-email-sasha.levin@oracle.com> * unvalidated timespec in io_getevents() - http://lkml.kernel.org/r/<CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@mail.gmail.com> * [NOTABUG] signed overflow in ktime_add_safe() - http://lkml.kernel.org/r/<CACT4Y+aJ4muRnWxsUe1CMnA6P8nooO33kwG-c8YZg=0Xc8rJqw@mail.gmail.com> [akpm@linux-foundation.org: fix unused local warning] [akpm@linux-foundation.org: fix __int128 build woes] Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Marek <mmarek@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Yury Gribov <y.gribov@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 23:00:55 +00:00
bool "Undefined behaviour sanity checker"
help
ubsan: add trap instrumentation option Patch series "ubsan: Split out bounds checker", v5. This splits out the bounds checker so it can be individually used. This is enabled in Android and hopefully for syzbot. Includes LKDTM tests for behavioral corner-cases (beyond just the bounds checker), and adjusts ubsan and kasan slightly for correct panic handling. This patch (of 6): The Undefined Behavior Sanitizer can operate in two modes: warning reporting mode via lib/ubsan.c handler calls, or trap mode, which uses __builtin_trap() as the handler. Using lib/ubsan.c means the kernel image is about 5% larger (due to all the debugging text and reporting structures to capture details about the warning conditions). Using the trap mode, the image size changes are much smaller, though at the loss of the "warning only" mode. In order to give greater flexibility to system builders that want minimal changes to image size and are prepared to deal with kernel code being aborted and potentially destabilizing the system, this introduces CONFIG_UBSAN_TRAP. The resulting image sizes comparison: text data bss dec hex filename 19533663 6183037 18554956 44271656 2a38828 vmlinux.stock 19991849 7618513 18874448 46484810 2c54d4a vmlinux.ubsan 19712181 6284181 18366540 44362902 2a4ec96 vmlinux.ubsan-trap CONFIG_UBSAN=y: image +4.8% (text +2.3%, data +18.9%) CONFIG_UBSAN_TRAP=y: image +0.2% (text +0.9%, data +1.6%) Additionally adjusts the CONFIG_UBSAN Kconfig help for clarity and removes the mention of non-existing boot param "ubsan_handle". Suggested-by: Elena Petrova <lenaptr@google.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Link: http://lkml.kernel.org/r/20200227193516.32566-2-keescook@chromium.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 03:12:27 +00:00
This option enables the Undefined Behaviour sanity checker.
UBSAN: run-time undefined behavior sanity checker UBSAN uses compile-time instrumentation to catch undefined behavior (UB). Compiler inserts code that perform certain kinds of checks before operations that could cause UB. If check fails (i.e. UB detected) __ubsan_handle_* function called to print error message. So the most of the work is done by compiler. This patch just implements ubsan handlers printing errors. GCC has this capability since 4.9.x [1] (see -fsanitize=undefined option and its suboptions). However GCC 5.x has more checkers implemented [2]. Article [3] has a bit more details about UBSAN in the GCC. [1] - https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html [2] - https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html [3] - http://developerblog.redhat.com/2014/10/16/gcc-undefined-behavior-sanitizer-ubsan/ Issues which UBSAN has found thus far are: Found bugs: * out-of-bounds access - 97840cb67ff5 ("netfilter: nfnetlink: fix insufficient validation in nfnetlink_bind") undefined shifts: * d48458d4a768 ("jbd2: use a better hash function for the revoke table") * 10632008b9e1 ("clockevents: Prevent shift out of bounds") * 'x << -1' shift in ext4 - http://lkml.kernel.org/r/<5444EF21.8020501@samsung.com> * undefined rol32(0) - http://lkml.kernel.org/r/<1449198241-20654-1-git-send-email-sasha.levin@oracle.com> * undefined dirty_ratelimit calculation - http://lkml.kernel.org/r/<566594E2.3050306@odin.com> * undefined roundown_pow_of_two(0) - http://lkml.kernel.org/r/<1449156616-11474-1-git-send-email-sasha.levin@oracle.com> * [WONTFIX] undefined shift in __bpf_prog_run - http://lkml.kernel.org/r/<CACT4Y+ZxoR3UjLgcNdUm4fECLMx2VdtfrENMtRRCdgHB2n0bJA@mail.gmail.com> WONTFIX here because it should be fixed in bpf program, not in kernel. signed overflows: * 32a8df4e0b33f ("sched: Fix odd values in effective_load() calculations") * mul overflow in ntp - http://lkml.kernel.org/r/<1449175608-1146-1-git-send-email-sasha.levin@oracle.com> * incorrect conversion into rtc_time in rtc_time64_to_tm() - http://lkml.kernel.org/r/<1449187944-11730-1-git-send-email-sasha.levin@oracle.com> * unvalidated timespec in io_getevents() - http://lkml.kernel.org/r/<CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@mail.gmail.com> * [NOTABUG] signed overflow in ktime_add_safe() - http://lkml.kernel.org/r/<CACT4Y+aJ4muRnWxsUe1CMnA6P8nooO33kwG-c8YZg=0Xc8rJqw@mail.gmail.com> [akpm@linux-foundation.org: fix unused local warning] [akpm@linux-foundation.org: fix __int128 build woes] Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Marek <mmarek@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Yury Gribov <y.gribov@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 23:00:55 +00:00
Compile-time instrumentation is used to detect various undefined
ubsan: add trap instrumentation option Patch series "ubsan: Split out bounds checker", v5. This splits out the bounds checker so it can be individually used. This is enabled in Android and hopefully for syzbot. Includes LKDTM tests for behavioral corner-cases (beyond just the bounds checker), and adjusts ubsan and kasan slightly for correct panic handling. This patch (of 6): The Undefined Behavior Sanitizer can operate in two modes: warning reporting mode via lib/ubsan.c handler calls, or trap mode, which uses __builtin_trap() as the handler. Using lib/ubsan.c means the kernel image is about 5% larger (due to all the debugging text and reporting structures to capture details about the warning conditions). Using the trap mode, the image size changes are much smaller, though at the loss of the "warning only" mode. In order to give greater flexibility to system builders that want minimal changes to image size and are prepared to deal with kernel code being aborted and potentially destabilizing the system, this introduces CONFIG_UBSAN_TRAP. The resulting image sizes comparison: text data bss dec hex filename 19533663 6183037 18554956 44271656 2a38828 vmlinux.stock 19991849 7618513 18874448 46484810 2c54d4a vmlinux.ubsan 19712181 6284181 18366540 44362902 2a4ec96 vmlinux.ubsan-trap CONFIG_UBSAN=y: image +4.8% (text +2.3%, data +18.9%) CONFIG_UBSAN_TRAP=y: image +0.2% (text +0.9%, data +1.6%) Additionally adjusts the CONFIG_UBSAN Kconfig help for clarity and removes the mention of non-existing boot param "ubsan_handle". Suggested-by: Elena Petrova <lenaptr@google.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Link: http://lkml.kernel.org/r/20200227193516.32566-2-keescook@chromium.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 03:12:27 +00:00
behaviours at runtime. For more details, see:
Documentation/dev-tools/ubsan.rst
ubsan: split "bounds" checker from other options In order to do kernel builds with the bounds checker individually available, introduce CONFIG_UBSAN_BOUNDS, with the remaining options under CONFIG_UBSAN_MISC. For example, using this, we can start to expand the coverage syzkaller is providing. Right now, all of UBSan is disabled for syzbot builds because taken as a whole, it is too noisy. This will let us focus on one feature at a time. For the bounds checker specifically, this provides a mechanism to eliminate an entire class of array overflows with close to zero performance overhead (I cannot measure a difference). In my (mostly) defconfig, enabling bounds checking adds ~4200 checks to the kernel. Performance changes are in the noise, likely due to the branch predictors optimizing for the non-fail path. Some notes on the bounds checker: - it does not instrument {mem,str}*()-family functions, it only instruments direct indexed accesses (e.g. "foo[i]"). Dealing with the {mem,str}*()-family functions is a work-in-progress around CONFIG_FORTIFY_SOURCE[1]. - it ignores flexible array members, including the very old single byte (e.g. "int foo[1];") declarations. (Note that GCC's implementation appears to ignore _all_ trailing arrays, but Clang only ignores empty, 0, and 1 byte arrays[2].) [1] https://github.com/KSPP/linux/issues/6 [2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92589 Suggested-by: Elena Petrova <lenaptr@google.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Dmitry Vyukov <dvyukov@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com> Link: http://lkml.kernel.org/r/20200227193516.32566-3-keescook@chromium.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 03:12:31 +00:00
if UBSAN
ubsan: add trap instrumentation option Patch series "ubsan: Split out bounds checker", v5. This splits out the bounds checker so it can be individually used. This is enabled in Android and hopefully for syzbot. Includes LKDTM tests for behavioral corner-cases (beyond just the bounds checker), and adjusts ubsan and kasan slightly for correct panic handling. This patch (of 6): The Undefined Behavior Sanitizer can operate in two modes: warning reporting mode via lib/ubsan.c handler calls, or trap mode, which uses __builtin_trap() as the handler. Using lib/ubsan.c means the kernel image is about 5% larger (due to all the debugging text and reporting structures to capture details about the warning conditions). Using the trap mode, the image size changes are much smaller, though at the loss of the "warning only" mode. In order to give greater flexibility to system builders that want minimal changes to image size and are prepared to deal with kernel code being aborted and potentially destabilizing the system, this introduces CONFIG_UBSAN_TRAP. The resulting image sizes comparison: text data bss dec hex filename 19533663 6183037 18554956 44271656 2a38828 vmlinux.stock 19991849 7618513 18874448 46484810 2c54d4a vmlinux.ubsan 19712181 6284181 18366540 44362902 2a4ec96 vmlinux.ubsan-trap CONFIG_UBSAN=y: image +4.8% (text +2.3%, data +18.9%) CONFIG_UBSAN_TRAP=y: image +0.2% (text +0.9%, data +1.6%) Additionally adjusts the CONFIG_UBSAN Kconfig help for clarity and removes the mention of non-existing boot param "ubsan_handle". Suggested-by: Elena Petrova <lenaptr@google.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Link: http://lkml.kernel.org/r/20200227193516.32566-2-keescook@chromium.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 03:12:27 +00:00
config UBSAN_TRAP
bool "On Sanitizer warnings, abort the running kernel code"
depends on !COMPILE_TEST
ubsan: add trap instrumentation option Patch series "ubsan: Split out bounds checker", v5. This splits out the bounds checker so it can be individually used. This is enabled in Android and hopefully for syzbot. Includes LKDTM tests for behavioral corner-cases (beyond just the bounds checker), and adjusts ubsan and kasan slightly for correct panic handling. This patch (of 6): The Undefined Behavior Sanitizer can operate in two modes: warning reporting mode via lib/ubsan.c handler calls, or trap mode, which uses __builtin_trap() as the handler. Using lib/ubsan.c means the kernel image is about 5% larger (due to all the debugging text and reporting structures to capture details about the warning conditions). Using the trap mode, the image size changes are much smaller, though at the loss of the "warning only" mode. In order to give greater flexibility to system builders that want minimal changes to image size and are prepared to deal with kernel code being aborted and potentially destabilizing the system, this introduces CONFIG_UBSAN_TRAP. The resulting image sizes comparison: text data bss dec hex filename 19533663 6183037 18554956 44271656 2a38828 vmlinux.stock 19991849 7618513 18874448 46484810 2c54d4a vmlinux.ubsan 19712181 6284181 18366540 44362902 2a4ec96 vmlinux.ubsan-trap CONFIG_UBSAN=y: image +4.8% (text +2.3%, data +18.9%) CONFIG_UBSAN_TRAP=y: image +0.2% (text +0.9%, data +1.6%) Additionally adjusts the CONFIG_UBSAN Kconfig help for clarity and removes the mention of non-existing boot param "ubsan_handle". Suggested-by: Elena Petrova <lenaptr@google.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Link: http://lkml.kernel.org/r/20200227193516.32566-2-keescook@chromium.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 03:12:27 +00:00
depends on $(cc-option, -fsanitize-undefined-trap-on-error)
help
Building kernels with Sanitizer features enabled tends to grow
the kernel size by around 5%, due to adding all the debugging
text on failure paths. To avoid this, Sanitizer instrumentation
can just issue a trap. This reduces the kernel size overhead but
turns all warnings (including potentially harmless conditions)
into full exceptions that abort the running kernel code
(regardless of context, locks held, etc), which may destabilize
the system. For some system builders this is an acceptable
trade-off.
UBSAN: run-time undefined behavior sanity checker UBSAN uses compile-time instrumentation to catch undefined behavior (UB). Compiler inserts code that perform certain kinds of checks before operations that could cause UB. If check fails (i.e. UB detected) __ubsan_handle_* function called to print error message. So the most of the work is done by compiler. This patch just implements ubsan handlers printing errors. GCC has this capability since 4.9.x [1] (see -fsanitize=undefined option and its suboptions). However GCC 5.x has more checkers implemented [2]. Article [3] has a bit more details about UBSAN in the GCC. [1] - https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html [2] - https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html [3] - http://developerblog.redhat.com/2014/10/16/gcc-undefined-behavior-sanitizer-ubsan/ Issues which UBSAN has found thus far are: Found bugs: * out-of-bounds access - 97840cb67ff5 ("netfilter: nfnetlink: fix insufficient validation in nfnetlink_bind") undefined shifts: * d48458d4a768 ("jbd2: use a better hash function for the revoke table") * 10632008b9e1 ("clockevents: Prevent shift out of bounds") * 'x << -1' shift in ext4 - http://lkml.kernel.org/r/<5444EF21.8020501@samsung.com> * undefined rol32(0) - http://lkml.kernel.org/r/<1449198241-20654-1-git-send-email-sasha.levin@oracle.com> * undefined dirty_ratelimit calculation - http://lkml.kernel.org/r/<566594E2.3050306@odin.com> * undefined roundown_pow_of_two(0) - http://lkml.kernel.org/r/<1449156616-11474-1-git-send-email-sasha.levin@oracle.com> * [WONTFIX] undefined shift in __bpf_prog_run - http://lkml.kernel.org/r/<CACT4Y+ZxoR3UjLgcNdUm4fECLMx2VdtfrENMtRRCdgHB2n0bJA@mail.gmail.com> WONTFIX here because it should be fixed in bpf program, not in kernel. signed overflows: * 32a8df4e0b33f ("sched: Fix odd values in effective_load() calculations") * mul overflow in ntp - http://lkml.kernel.org/r/<1449175608-1146-1-git-send-email-sasha.levin@oracle.com> * incorrect conversion into rtc_time in rtc_time64_to_tm() - http://lkml.kernel.org/r/<1449187944-11730-1-git-send-email-sasha.levin@oracle.com> * unvalidated timespec in io_getevents() - http://lkml.kernel.org/r/<CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@mail.gmail.com> * [NOTABUG] signed overflow in ktime_add_safe() - http://lkml.kernel.org/r/<CACT4Y+aJ4muRnWxsUe1CMnA6P8nooO33kwG-c8YZg=0Xc8rJqw@mail.gmail.com> [akpm@linux-foundation.org: fix unused local warning] [akpm@linux-foundation.org: fix __int128 build woes] Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Marek <mmarek@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Yury Gribov <y.gribov@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 23:00:55 +00:00
config UBSAN_KCOV_BROKEN
def_bool KCOV && CC_HAS_SANCOV_TRACE_PC
depends on CC_IS_CLANG
depends on !$(cc-option,-Werror=unused-command-line-argument -fsanitize=bounds -fsanitize-coverage=trace-pc)
help
Some versions of clang support either UBSAN or KCOV but not the
combination of the two.
See https://bugs.llvm.org/show_bug.cgi?id=45831 for the status
in newer releases.
config CC_HAS_UBSAN_BOUNDS
def_bool $(cc-option,-fsanitize=bounds)
config CC_HAS_UBSAN_ARRAY_BOUNDS
def_bool $(cc-option,-fsanitize=array-bounds)
ubsan: split "bounds" checker from other options In order to do kernel builds with the bounds checker individually available, introduce CONFIG_UBSAN_BOUNDS, with the remaining options under CONFIG_UBSAN_MISC. For example, using this, we can start to expand the coverage syzkaller is providing. Right now, all of UBSan is disabled for syzbot builds because taken as a whole, it is too noisy. This will let us focus on one feature at a time. For the bounds checker specifically, this provides a mechanism to eliminate an entire class of array overflows with close to zero performance overhead (I cannot measure a difference). In my (mostly) defconfig, enabling bounds checking adds ~4200 checks to the kernel. Performance changes are in the noise, likely due to the branch predictors optimizing for the non-fail path. Some notes on the bounds checker: - it does not instrument {mem,str}*()-family functions, it only instruments direct indexed accesses (e.g. "foo[i]"). Dealing with the {mem,str}*()-family functions is a work-in-progress around CONFIG_FORTIFY_SOURCE[1]. - it ignores flexible array members, including the very old single byte (e.g. "int foo[1];") declarations. (Note that GCC's implementation appears to ignore _all_ trailing arrays, but Clang only ignores empty, 0, and 1 byte arrays[2].) [1] https://github.com/KSPP/linux/issues/6 [2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92589 Suggested-by: Elena Petrova <lenaptr@google.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Dmitry Vyukov <dvyukov@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com> Link: http://lkml.kernel.org/r/20200227193516.32566-3-keescook@chromium.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 03:12:31 +00:00
config UBSAN_BOUNDS
bool "Perform array index bounds checking"
default UBSAN
depends on !UBSAN_KCOV_BROKEN
depends on CC_HAS_UBSAN_ARRAY_BOUNDS || CC_HAS_UBSAN_BOUNDS
ubsan: split "bounds" checker from other options In order to do kernel builds with the bounds checker individually available, introduce CONFIG_UBSAN_BOUNDS, with the remaining options under CONFIG_UBSAN_MISC. For example, using this, we can start to expand the coverage syzkaller is providing. Right now, all of UBSan is disabled for syzbot builds because taken as a whole, it is too noisy. This will let us focus on one feature at a time. For the bounds checker specifically, this provides a mechanism to eliminate an entire class of array overflows with close to zero performance overhead (I cannot measure a difference). In my (mostly) defconfig, enabling bounds checking adds ~4200 checks to the kernel. Performance changes are in the noise, likely due to the branch predictors optimizing for the non-fail path. Some notes on the bounds checker: - it does not instrument {mem,str}*()-family functions, it only instruments direct indexed accesses (e.g. "foo[i]"). Dealing with the {mem,str}*()-family functions is a work-in-progress around CONFIG_FORTIFY_SOURCE[1]. - it ignores flexible array members, including the very old single byte (e.g. "int foo[1];") declarations. (Note that GCC's implementation appears to ignore _all_ trailing arrays, but Clang only ignores empty, 0, and 1 byte arrays[2].) [1] https://github.com/KSPP/linux/issues/6 [2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92589 Suggested-by: Elena Petrova <lenaptr@google.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Dmitry Vyukov <dvyukov@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com> Link: http://lkml.kernel.org/r/20200227193516.32566-3-keescook@chromium.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 03:12:31 +00:00
help
This option enables detection of directly indexed out of bounds
array accesses, where the array size is known at compile time.
Note that this does not protect array overflows via bad calls
to the {str,mem}*cpy() family of functions (that is addressed
by CONFIG_FORTIFY_SOURCE).
config UBSAN_ONLY_BOUNDS
def_bool CC_HAS_UBSAN_BOUNDS && !CC_HAS_UBSAN_ARRAY_BOUNDS
depends on UBSAN_BOUNDS
help
This is a weird case: Clang's -fsanitize=bounds includes
-fsanitize=local-bounds, but it's trapping-only, so for
Clang, we must use -fsanitize=array-bounds when we want
traditional array bounds checking enabled. For GCC, we
want -fsanitize=bounds.
config UBSAN_ARRAY_BOUNDS
def_bool CC_HAS_UBSAN_ARRAY_BOUNDS
depends on UBSAN_BOUNDS
ubsan: introduce CONFIG_UBSAN_LOCAL_BOUNDS for Clang When the kernel is compiled with Clang, -fsanitize=bounds expands to -fsanitize=array-bounds and -fsanitize=local-bounds. Enabling -fsanitize=local-bounds with Clang has the unfortunate side-effect of inserting traps; this goes back to its original intent, which was as a hardening and not a debugging feature [1]. The same feature made its way into -fsanitize=bounds, but the traps remained. For that reason, -fsanitize=bounds was split into 'array-bounds' and 'local-bounds' [2]. Since 'local-bounds' doesn't behave like a normal sanitizer, enable it with Clang only if trapping behaviour was requested by CONFIG_UBSAN_TRAP=y. Add the UBSAN_BOUNDS_LOCAL config to Kconfig.ubsan to enable the 'local-bounds' option by default when UBSAN_TRAP is enabled. [1] http://lists.llvm.org/pipermail/llvm-dev/2012-May/049972.html [2] http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20131021/091536.html Suggested-by: Marco Elver <elver@google.com> Signed-off-by: George Popescu <georgepope@android.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Brazdil <dbrazdil@google.com> Reviewed-by: Marco Elver <elver@google.com> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Nathan Chancellor <natechancellor@gmail.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: https://lkml.kernel.org/r/20200922074330.2549523-1-georgepope@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-16 03:13:38 +00:00
config UBSAN_LOCAL_BOUNDS
bool "Perform array local bounds checking"
depends on UBSAN_TRAP
depends on !UBSAN_KCOV_BROKEN
depends on $(cc-option,-fsanitize=local-bounds)
ubsan: introduce CONFIG_UBSAN_LOCAL_BOUNDS for Clang When the kernel is compiled with Clang, -fsanitize=bounds expands to -fsanitize=array-bounds and -fsanitize=local-bounds. Enabling -fsanitize=local-bounds with Clang has the unfortunate side-effect of inserting traps; this goes back to its original intent, which was as a hardening and not a debugging feature [1]. The same feature made its way into -fsanitize=bounds, but the traps remained. For that reason, -fsanitize=bounds was split into 'array-bounds' and 'local-bounds' [2]. Since 'local-bounds' doesn't behave like a normal sanitizer, enable it with Clang only if trapping behaviour was requested by CONFIG_UBSAN_TRAP=y. Add the UBSAN_BOUNDS_LOCAL config to Kconfig.ubsan to enable the 'local-bounds' option by default when UBSAN_TRAP is enabled. [1] http://lists.llvm.org/pipermail/llvm-dev/2012-May/049972.html [2] http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20131021/091536.html Suggested-by: Marco Elver <elver@google.com> Signed-off-by: George Popescu <georgepope@android.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Brazdil <dbrazdil@google.com> Reviewed-by: Marco Elver <elver@google.com> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Nathan Chancellor <natechancellor@gmail.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: https://lkml.kernel.org/r/20200922074330.2549523-1-georgepope@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-16 03:13:38 +00:00
help
This option enables -fsanitize=local-bounds which traps when an
exception/error is detected. Therefore, it may only be enabled
with CONFIG_UBSAN_TRAP.
ubsan: introduce CONFIG_UBSAN_LOCAL_BOUNDS for Clang When the kernel is compiled with Clang, -fsanitize=bounds expands to -fsanitize=array-bounds and -fsanitize=local-bounds. Enabling -fsanitize=local-bounds with Clang has the unfortunate side-effect of inserting traps; this goes back to its original intent, which was as a hardening and not a debugging feature [1]. The same feature made its way into -fsanitize=bounds, but the traps remained. For that reason, -fsanitize=bounds was split into 'array-bounds' and 'local-bounds' [2]. Since 'local-bounds' doesn't behave like a normal sanitizer, enable it with Clang only if trapping behaviour was requested by CONFIG_UBSAN_TRAP=y. Add the UBSAN_BOUNDS_LOCAL config to Kconfig.ubsan to enable the 'local-bounds' option by default when UBSAN_TRAP is enabled. [1] http://lists.llvm.org/pipermail/llvm-dev/2012-May/049972.html [2] http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20131021/091536.html Suggested-by: Marco Elver <elver@google.com> Signed-off-by: George Popescu <georgepope@android.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: David Brazdil <dbrazdil@google.com> Reviewed-by: Marco Elver <elver@google.com> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Michal Marek <michal.lkml@markovi.net> Cc: Nathan Chancellor <natechancellor@gmail.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: https://lkml.kernel.org/r/20200922074330.2549523-1-georgepope@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-16 03:13:38 +00:00
Enabling this option detects errors due to accesses through a
pointer that is derived from an object of a statically-known size,
where an added offset (which may not be known statically) is
out-of-bounds.
config UBSAN_SHIFT
bool "Perform checking for bit-shift overflows"
default UBSAN
depends on $(cc-option,-fsanitize=shift)
help
This option enables -fsanitize=shift which checks for bit-shift
operations that overflow to the left or go switch to negative
for signed types.
config UBSAN_DIV_ZERO
bool "Perform checking for integer divide-by-zero"
depends on $(cc-option,-fsanitize=integer-divide-by-zero)
help
This option enables -fsanitize=integer-divide-by-zero which checks
for integer division by zero. This is effectively redundant with the
kernel's existing exception handling, though it can provide greater
debugging information under CONFIG_UBSAN_REPORT_FULL.
config UBSAN_UNREACHABLE
bool "Perform checking for unreachable code"
# objtool already handles unreachable checking and gets angry about
# seeing UBSan instrumentation located in unreachable places.
depends on !STACK_VALIDATION
depends on $(cc-option,-fsanitize=unreachable)
help
This option enables -fsanitize=unreachable which checks for control
flow reaching an expected-to-be-unreachable position.
config UBSAN_SIGNED_OVERFLOW
bool "Perform checking for signed arithmetic overflow"
default UBSAN
depends on $(cc-option,-fsanitize=signed-integer-overflow)
help
This option enables -fsanitize=signed-integer-overflow which checks
for overflow of any arithmetic operations with signed integers.
config UBSAN_UNSIGNED_OVERFLOW
bool "Perform checking for unsigned arithmetic overflow"
depends on $(cc-option,-fsanitize=unsigned-integer-overflow)
ubsan: disable unsigned-overflow check for i386 Building ubsan kernels even for compile-testing introduced these warnings in my randconfig environment: crypto/blake2b_generic.c:98:13: error: stack frame size of 9636 bytes in function 'blake2b_compress' [-Werror,-Wframe-larger-than=] static void blake2b_compress(struct blake2b_state *S, crypto/sha512_generic.c:151:13: error: stack frame size of 1292 bytes in function 'sha512_generic_block_fn' [-Werror,-Wframe-larger-than=] static void sha512_generic_block_fn(struct sha512_state *sst, u8 const *src, lib/crypto/curve25519-fiat32.c:312:22: error: stack frame size of 2180 bytes in function 'fe_mul_impl' [-Werror,-Wframe-larger-than=] static noinline void fe_mul_impl(u32 out[10], const u32 in1[10], const u32 in2[10]) lib/crypto/curve25519-fiat32.c:444:22: error: stack frame size of 1588 bytes in function 'fe_sqr_impl' [-Werror,-Wframe-larger-than=] static noinline void fe_sqr_impl(u32 out[10], const u32 in1[10]) Further testing showed that this is caused by -fsanitize=unsigned-integer-overflow, but is isolated to the 32-bit x86 architecture. The one in blake2b immediately overflows the 8KB stack area architectures, so better ensure this never happens by disabling the option for 32-bit x86. Link: https://lkml.kernel.org/r/20210112202922.2454435-1-arnd@kernel.org Link: https://lore.kernel.org/lkml/20201230154749.746641-1-arnd@kernel.org/ Fixes: d0a3ac549f38 ("ubsan: enable for all*config builds") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Kees Cook <keescook@chromium.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Marco Elver <elver@google.com> Cc: George Popescu <georgepope@android.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-01-24 05:01:48 +00:00
depends on !X86_32 # avoid excessive stack usage on x86-32/clang
help
This option enables -fsanitize=unsigned-integer-overflow which checks
for overflow of any arithmetic operations with unsigned integers. This
currently causes x86 to fail to boot.
config UBSAN_OBJECT_SIZE
bool "Perform checking for accesses beyond the end of objects"
default UBSAN
# gcc hugely expands stack usage with -fsanitize=object-size
# https://lore.kernel.org/lkml/CAHk-=wjPasyJrDuwDnpHJS2TuQfExwe=px-SzLeN8GFMAQJPmQ@mail.gmail.com/
depends on !CC_IS_GCC
depends on $(cc-option,-fsanitize=object-size)
help
This option enables -fsanitize=object-size which checks for accesses
beyond the end of objects where the optimizer can determine both the
object being operated on and its size, usually seen with bad downcasts,
or access to struct members from NULL pointers.
config UBSAN_BOOL
bool "Perform checking for non-boolean values used as boolean"
default UBSAN
depends on $(cc-option,-fsanitize=bool)
help
This option enables -fsanitize=bool which checks for boolean values being
loaded that are neither 0 nor 1.
config UBSAN_ENUM
bool "Perform checking for out of bounds enum values"
default UBSAN
depends on $(cc-option,-fsanitize=enum)
help
This option enables -fsanitize=enum which checks for values being loaded
into an enum that are outside the range of given values for the given enum.
config UBSAN_ALIGNMENT
bool "Perform checking for misaligned pointer usage"
default !HAVE_EFFICIENT_UNALIGNED_ACCESS
depends on !UBSAN_TRAP && !COMPILE_TEST
depends on $(cc-option,-fsanitize=alignment)
help
This option enables the check of unaligned memory accesses.
Enabling this option on architectures that support unaligned
accesses may produce a lot of false positives.
UBSAN: run-time undefined behavior sanity checker UBSAN uses compile-time instrumentation to catch undefined behavior (UB). Compiler inserts code that perform certain kinds of checks before operations that could cause UB. If check fails (i.e. UB detected) __ubsan_handle_* function called to print error message. So the most of the work is done by compiler. This patch just implements ubsan handlers printing errors. GCC has this capability since 4.9.x [1] (see -fsanitize=undefined option and its suboptions). However GCC 5.x has more checkers implemented [2]. Article [3] has a bit more details about UBSAN in the GCC. [1] - https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html [2] - https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html [3] - http://developerblog.redhat.com/2014/10/16/gcc-undefined-behavior-sanitizer-ubsan/ Issues which UBSAN has found thus far are: Found bugs: * out-of-bounds access - 97840cb67ff5 ("netfilter: nfnetlink: fix insufficient validation in nfnetlink_bind") undefined shifts: * d48458d4a768 ("jbd2: use a better hash function for the revoke table") * 10632008b9e1 ("clockevents: Prevent shift out of bounds") * 'x << -1' shift in ext4 - http://lkml.kernel.org/r/<5444EF21.8020501@samsung.com> * undefined rol32(0) - http://lkml.kernel.org/r/<1449198241-20654-1-git-send-email-sasha.levin@oracle.com> * undefined dirty_ratelimit calculation - http://lkml.kernel.org/r/<566594E2.3050306@odin.com> * undefined roundown_pow_of_two(0) - http://lkml.kernel.org/r/<1449156616-11474-1-git-send-email-sasha.levin@oracle.com> * [WONTFIX] undefined shift in __bpf_prog_run - http://lkml.kernel.org/r/<CACT4Y+ZxoR3UjLgcNdUm4fECLMx2VdtfrENMtRRCdgHB2n0bJA@mail.gmail.com> WONTFIX here because it should be fixed in bpf program, not in kernel. signed overflows: * 32a8df4e0b33f ("sched: Fix odd values in effective_load() calculations") * mul overflow in ntp - http://lkml.kernel.org/r/<1449175608-1146-1-git-send-email-sasha.levin@oracle.com> * incorrect conversion into rtc_time in rtc_time64_to_tm() - http://lkml.kernel.org/r/<1449187944-11730-1-git-send-email-sasha.levin@oracle.com> * unvalidated timespec in io_getevents() - http://lkml.kernel.org/r/<CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@mail.gmail.com> * [NOTABUG] signed overflow in ktime_add_safe() - http://lkml.kernel.org/r/<CACT4Y+aJ4muRnWxsUe1CMnA6P8nooO33kwG-c8YZg=0Xc8rJqw@mail.gmail.com> [akpm@linux-foundation.org: fix unused local warning] [akpm@linux-foundation.org: fix __int128 build woes] Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Marek <mmarek@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Yury Gribov <y.gribov@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 23:00:55 +00:00
config UBSAN_SANITIZE_ALL
bool "Enable instrumentation for the entire kernel"
depends on ARCH_HAS_UBSAN_SANITIZE_ALL
default y
help
This option activates instrumentation for the entire kernel.
If you don't enable this option, you have to explicitly specify
UBSAN_SANITIZE := y for the files/directories you want to check for UB.
Enabling this option will get kernel image size increased
significantly.
UBSAN: run-time undefined behavior sanity checker UBSAN uses compile-time instrumentation to catch undefined behavior (UB). Compiler inserts code that perform certain kinds of checks before operations that could cause UB. If check fails (i.e. UB detected) __ubsan_handle_* function called to print error message. So the most of the work is done by compiler. This patch just implements ubsan handlers printing errors. GCC has this capability since 4.9.x [1] (see -fsanitize=undefined option and its suboptions). However GCC 5.x has more checkers implemented [2]. Article [3] has a bit more details about UBSAN in the GCC. [1] - https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html [2] - https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html [3] - http://developerblog.redhat.com/2014/10/16/gcc-undefined-behavior-sanitizer-ubsan/ Issues which UBSAN has found thus far are: Found bugs: * out-of-bounds access - 97840cb67ff5 ("netfilter: nfnetlink: fix insufficient validation in nfnetlink_bind") undefined shifts: * d48458d4a768 ("jbd2: use a better hash function for the revoke table") * 10632008b9e1 ("clockevents: Prevent shift out of bounds") * 'x << -1' shift in ext4 - http://lkml.kernel.org/r/<5444EF21.8020501@samsung.com> * undefined rol32(0) - http://lkml.kernel.org/r/<1449198241-20654-1-git-send-email-sasha.levin@oracle.com> * undefined dirty_ratelimit calculation - http://lkml.kernel.org/r/<566594E2.3050306@odin.com> * undefined roundown_pow_of_two(0) - http://lkml.kernel.org/r/<1449156616-11474-1-git-send-email-sasha.levin@oracle.com> * [WONTFIX] undefined shift in __bpf_prog_run - http://lkml.kernel.org/r/<CACT4Y+ZxoR3UjLgcNdUm4fECLMx2VdtfrENMtRRCdgHB2n0bJA@mail.gmail.com> WONTFIX here because it should be fixed in bpf program, not in kernel. signed overflows: * 32a8df4e0b33f ("sched: Fix odd values in effective_load() calculations") * mul overflow in ntp - http://lkml.kernel.org/r/<1449175608-1146-1-git-send-email-sasha.levin@oracle.com> * incorrect conversion into rtc_time in rtc_time64_to_tm() - http://lkml.kernel.org/r/<1449187944-11730-1-git-send-email-sasha.levin@oracle.com> * unvalidated timespec in io_getevents() - http://lkml.kernel.org/r/<CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@mail.gmail.com> * [NOTABUG] signed overflow in ktime_add_safe() - http://lkml.kernel.org/r/<CACT4Y+aJ4muRnWxsUe1CMnA6P8nooO33kwG-c8YZg=0Xc8rJqw@mail.gmail.com> [akpm@linux-foundation.org: fix unused local warning] [akpm@linux-foundation.org: fix __int128 build woes] Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Michal Marek <mmarek@suse.cz> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Yury Gribov <y.gribov@samsung.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Kostya Serebryany <kcc@google.com> Cc: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-20 23:00:55 +00:00
config TEST_UBSAN
tristate "Module for testing for undefined behavior detection"
ubsan: split "bounds" checker from other options In order to do kernel builds with the bounds checker individually available, introduce CONFIG_UBSAN_BOUNDS, with the remaining options under CONFIG_UBSAN_MISC. For example, using this, we can start to expand the coverage syzkaller is providing. Right now, all of UBSan is disabled for syzbot builds because taken as a whole, it is too noisy. This will let us focus on one feature at a time. For the bounds checker specifically, this provides a mechanism to eliminate an entire class of array overflows with close to zero performance overhead (I cannot measure a difference). In my (mostly) defconfig, enabling bounds checking adds ~4200 checks to the kernel. Performance changes are in the noise, likely due to the branch predictors optimizing for the non-fail path. Some notes on the bounds checker: - it does not instrument {mem,str}*()-family functions, it only instruments direct indexed accesses (e.g. "foo[i]"). Dealing with the {mem,str}*()-family functions is a work-in-progress around CONFIG_FORTIFY_SOURCE[1]. - it ignores flexible array members, including the very old single byte (e.g. "int foo[1];") declarations. (Note that GCC's implementation appears to ignore _all_ trailing arrays, but Clang only ignores empty, 0, and 1 byte arrays[2].) [1] https://github.com/KSPP/linux/issues/6 [2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92589 Suggested-by: Elena Petrova <lenaptr@google.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Dmitry Vyukov <dvyukov@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com> Link: http://lkml.kernel.org/r/20200227193516.32566-3-keescook@chromium.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 03:12:31 +00:00
depends on m
help
This is a test module for UBSAN.
It triggers various undefined behavior, and detect it.
ubsan: split "bounds" checker from other options In order to do kernel builds with the bounds checker individually available, introduce CONFIG_UBSAN_BOUNDS, with the remaining options under CONFIG_UBSAN_MISC. For example, using this, we can start to expand the coverage syzkaller is providing. Right now, all of UBSan is disabled for syzbot builds because taken as a whole, it is too noisy. This will let us focus on one feature at a time. For the bounds checker specifically, this provides a mechanism to eliminate an entire class of array overflows with close to zero performance overhead (I cannot measure a difference). In my (mostly) defconfig, enabling bounds checking adds ~4200 checks to the kernel. Performance changes are in the noise, likely due to the branch predictors optimizing for the non-fail path. Some notes on the bounds checker: - it does not instrument {mem,str}*()-family functions, it only instruments direct indexed accesses (e.g. "foo[i]"). Dealing with the {mem,str}*()-family functions is a work-in-progress around CONFIG_FORTIFY_SOURCE[1]. - it ignores flexible array members, including the very old single byte (e.g. "int foo[1];") declarations. (Note that GCC's implementation appears to ignore _all_ trailing arrays, but Clang only ignores empty, 0, and 1 byte arrays[2].) [1] https://github.com/KSPP/linux/issues/6 [2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92589 Suggested-by: Elena Petrova <lenaptr@google.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Dmitry Vyukov <dvyukov@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: "Gustavo A. R. Silva" <gustavo@embeddedor.com> Link: http://lkml.kernel.org/r/20200227193516.32566-3-keescook@chromium.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-07 03:12:31 +00:00
endif # if UBSAN