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57b6de08b5
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Eric W. Biederman 57b6de08b5 ptrace: Admit ptrace_stop can generate spuriuos SIGTRAPs 
Long ago and far away there was a BUG_ON at the start of ptrace_stop
that did "BUG_ON(!(current->ptrace & PT_PTRACED));" [1].  The BUG_ON
had never triggered but examination of the code showed that the BUG_ON
could actually trigger.  To complement removing the BUG_ON an attempt
to better handle the race was added.

The code detected the tracer had gone away and did not call
do_notify_parent_cldstop.  The code also attempted to prevent
ptrace_report_syscall from sending spurious SIGTRAPs when the tracer
went away.

The code to detect when the tracer had gone away before sending a
signal to tracer was a legitimate fix and continues to work to this
date.

The code to prevent sending spurious SIGTRAPs is a failure.  At the
time and until today the code only catches it when the tracer goes
away after siglock is dropped and before read_lock is acquired.  If
the tracer goes away after read_lock is dropped a spurious SIGTRAP can
still be sent to the tracee.  The tracer going away after read_lock
is dropped is the far likelier case as it is the bigger window.

Given that the attempt to prevent the generation of a SIGTRAP was a
failure and continues to be a failure remove the code that attempts to
do that.  This simplifies the code in ptrace_stop and makes
ptrace_stop much easier to reason about.

To successfully deal with the tracer going away, all of the tracer's
instrumentation of the child would need to be removed, and reliably
detecting when the tracer has set a signal to continue with would need
to be implemented.

[1] 66519f549ae5 ("[PATCH] fix ptracer death race yielding bogus BUG_ON")
History-Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Tested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lkml.kernel.org/r/20220505182645.497868-9-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2022-05-11 14:35:00 -05:00
..
bpf bpf: Fix maximum permitted number of arguments check 2022-03-28 19:08:17 -07:00
cgroup Driver core changes for 5.18-rc1 2022-03-28 12:41:28 -07:00
configs Char/Misc and other driver updates for 5.18-rc1 2022-03-28 12:27:35 -07:00
debug kdb: Fix the putarea helper function 2022-03-24 16:39:47 +00:00
dma dma-mapping: move pgprot_decrypted out of dma_pgprot 2022-04-01 06:46:51 +02:00
entry Revert "signal, x86: Delay calling signals in atomic on RT enabled kernels" 2022-03-31 10:36:55 +02:00
events asm-generic updates for 5.18 2022-03-23 18:03:08 -07:00
futex mm/truncate: Inline invalidate_complete_page() into its one caller 2022-03-21 12:59:01 -04:00
gcov gcov: Remove compiler version check 2021-12-02 17:25:21 +09:00
irq Changes in this cycle were: 2022-03-22 14:39:12 -07:00
kcsan KCSAN updates for v5.17 2022-01-11 09:51:26 -08:00
livepatch ptrace: Cleanups for v5.18 2022-03-28 17:29:53 -07:00
locking Changes in this cycle were: 2022-03-22 13:44:21 -07:00
power for-5.18/block-2022-03-18 2022-03-21 16:48:55 -07:00
printk printk changes for 5.18 2022-03-23 10:54:27 -07:00
rcu Changes in this cycle were: 2022-03-22 14:39:12 -07:00
sched ptrace: Cleanups for v5.18 2022-03-28 17:29:53 -07:00
time signal: Replace __group_send_sig_info with send_signal_locked 2022-05-11 14:33:17 -05:00
trace Updates to Tracing: 2022-04-03 12:26:01 -07:00
.gitignore
acct.c kernel: remove spurious blkdev.h includes 2021-10-18 06:17:01 -06:00
async.c Revert "module, async: async_synchronize_full() on module init iff async is used" 2022-02-03 11:20:34 -08:00
audit_fsnotify.c fsnotify: clarify contract for create event hooks 2021-10-27 12:32:34 +02:00
audit_tree.c audit: use struct_size() helper in kmalloc() 2021-12-14 17:39:42 -05:00
audit_watch.c \n 2021-11-06 16:43:20 -07:00
audit.c audit: improve audit queue handling when "audit=1" on cmdline 2022-01-25 13:22:51 -05:00
audit.h audit: log AUDIT_TIME_* records only from rules 2022-02-22 13:51:40 -05:00
auditfilter.c audit/stable-5.17 PR 20220110 2022-01-11 13:08:21 -08:00
auditsc.c audit/stable-5.18 PR 20220321 2022-03-21 20:53:11 -07:00
backtracetest.c
bounds.c
capability.c xfs: don't generate selinux audit messages for capability testing 2022-03-09 10:32:06 -08:00
cfi.c cfi: Use rcu_read_{un}lock_sched_notrace 2021-08-11 13:11:12 -07:00
compat.c arch: remove compat_alloc_user_space 2021-09-08 15:32:35 -07:00
configs.c
context_tracking.c
cpu_pm.c PM: cpu: Make notifier chain use a raw_spinlock_t 2021-08-16 18:55:32 +02:00
cpu.c Changes in this cycle were: 2022-03-22 14:39:12 -07:00
crash_core.c kernel/crash_core: suppress unknown crashkernel parameter warning 2021-12-25 12:20:55 -08:00
crash_dump.c
cred.c x86: Mark __invalid_creds() __noreturn 2022-03-15 10:32:44 +01:00
delayacct.c delayacct: track delays from memory compact 2022-01-20 08:52:55 +02:00
dma.c
exec_domain.c
exit.c ptrace: Cleanups for v5.18 2022-03-28 17:29:53 -07:00
extable.c lkdtm: Really write into kernel text in WRITE_KERN 2022-02-16 23:25:12 +11:00
fail_function.c
fork.c kasan, arm64: reset pointer tags of vmapped stacks 2022-03-24 19:06:47 -07:00
freezer.c sched: Add get_current_state() 2021-06-18 11:43:08 +02:00
gen_kheaders.sh kbuild: clean up ${quiet} checks in shell scripts 2021-05-27 04:01:50 +09:00
groups.c
hung_task.c hung_task: move hung_task sysctl interface to hung_task.c 2022-01-22 08:33:34 +02:00
iomem.c
irq_work.c irq_work: Also rcuwait for !IRQ_WORK_HARD_IRQ on PREEMPT_RT 2021-10-15 11:25:18 +02:00
jump_label.c jump_label: Fix jump_label_text_reserved() vs __init 2021-07-05 10:46:20 +02:00
kallsyms.c kallsyms: Skip the name search for empty string 2022-03-17 20:17:18 -07:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks locking/rwlock: Provide RT variant 2021-08-17 17:50:51 +02:00
Kconfig.preempt Revert "signal, x86: Delay calling signals in atomic on RT enabled kernels" 2022-03-31 10:36:55 +02:00
kcov.c kcov: properly handle subsequent mmap calls 2022-03-23 19:00:35 -07:00
kexec_core.c exit: Move oops specific logic from do_exit into make_task_dead 2021-12-13 12:04:45 -06:00
kexec_elf.c
kexec_file.c memblock: add MEMBLOCK_DRIVER_MANAGED to mimic IORESOURCE_SYSRAM_DRIVER_MANAGED 2021-11-06 13:30:42 -07:00
kexec_internal.h
kexec.c kexec: avoid compat_alloc_user_space 2021-09-08 15:32:34 -07:00
kheaders.c
kmod.c
kprobes.c kprobes: Use rethook for kretprobe if possible 2022-03-28 19:38:09 -07:00
ksysfs.c kernel/ksysfs.c: use helper macro __ATTR_RW 2022-03-23 19:00:33 -07:00
kthread.c asm-generic updates for 5.18 2022-03-23 18:03:08 -07:00
latencytop.c
Makefile kprobes: Use rethook for kretprobe if possible 2022-03-28 19:38:09 -07:00
module_decompress.c module: fix building with sysfs disabled 2022-02-16 12:51:32 -08:00
module_signature.c
module_signing.c
module-internal.h module: add in-kernel support for decompressing 2022-01-11 18:45:02 -08:00
module.c NFSD: Remove svc_serv_ops::svo_module 2022-02-28 10:26:40 -05:00
notifier.c notifier: Return an error when a callback has already been registered 2021-12-29 10:37:33 +01:00
nsproxy.c memcg: enable accounting for new namesapces and struct nsproxy 2021-09-03 09:58:12 -07:00
padata.c padata: replace cpumask_weight with cpumask_empty in padata.c 2022-01-31 11:21:46 +11:00
panic.c panic: move panic_print before kmsg dumpers 2022-03-23 19:00:35 -07:00
params.c kobject: remove kset from struct kset_uevent_ops callbacks 2021-12-28 11:26:18 +01:00
pid_namespace.c memcg: enable accounting for new namesapces and struct nsproxy 2021-09-03 09:58:12 -07:00
pid.c pid: add pidfd_get_task() helper 2021-10-14 13:29:18 +02:00
profile.c exit: Remove profile_handoff_task 2022-01-08 12:43:57 -06:00
ptrace.c ptrace: Document that wait_task_inactive can't fail 2022-05-11 14:34:47 -05:00
range.c
reboot.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2021-11-12 11:53:16 -08:00
regset.c
relay.c
resource_kunit.c
resource.c kernel/resource: fix kfree() of bootmem memory again 2022-03-23 19:00:35 -07:00
rseq.c rseq: Remove broken uapi field layout on 32-bit little endian 2022-02-02 13:11:34 +01:00
scftorture.c scftorture: Always log error message 2021-12-07 16:36:17 -08:00
scs.c kasan, vmalloc: only tag normal vmalloc allocations 2022-03-24 19:06:48 -07:00
seccomp.c ptrace: Cleanups for v5.18 2022-03-28 17:29:53 -07:00
signal.c ptrace: Admit ptrace_stop can generate spuriuos SIGTRAPs 2022-05-11 14:35:00 -05:00
smp.c sched: Improve wake_up_all_idle_cpus() take #2 2021-10-22 15:32:46 +02:00
smpboot.c smpboot: Replace deprecated CPU-hotplug functions. 2021-08-10 14:57:42 +02:00
smpboot.h
softirq.c genirq, softirq: Use in_hardirq() instead of in_irq() 2022-02-02 21:34:19 +01:00
stackleak.c gcc-plugins/stackleak: Use noinstr in favor of notrace 2022-02-03 17:02:21 -08:00
stacktrace.c uaccess: remove CONFIG_SET_FS 2022-02-25 09:36:06 +01:00
static_call.c KVM: x86: allow defining return-0 static calls 2022-02-18 12:44:22 -05:00
stop_machine.c
sys_ni.c mm/mempolicy: wire up syscall set_mempolicy_home_node 2022-01-15 16:30:30 +02:00
sys.c prlimit: do not grab the tasklist_lock 2022-03-08 14:33:36 -06:00
sysctl-test.c kernel/sysctl-test: Remove some casts which are no-longer required 2021-06-23 16:41:24 -06:00
sysctl.c Merge branch 'akpm' (patches from Andrew) 2022-03-22 16:11:53 -07:00
task_work.c resume_user_mode: Move to resume_user_mode.h 2022-03-10 16:51:50 -06:00
taskstats.c taskstats: remove unneeded dead assignment 2022-03-23 19:00:35 -07:00
torture.c torture: Wake up kthreads after storing task_struct pointer 2022-02-01 17:24:39 -08:00
tracepoint.c tracepoint: Fix kerneldoc comments 2021-08-16 11:39:51 -04:00
tsacct.c taskstats: Cleanup the use of task->exit_code 2022-01-08 12:43:57 -06:00
ucount.c ucounts: Handle wrapping in is_ucounts_overlimit 2022-02-17 09:11:57 -06:00
uid16.c
uid16.h
umh.c
up.c
user_namespace.c ucounts: Fix systemd LimitNPROC with private users regression 2022-02-25 10:40:14 -06:00
user-return-notifier.c
user.c fs/epoll: use a per-cpu counter for user's watches count 2021-09-08 11:50:27 -07:00
usermode_driver.c Merge branch 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-07-03 11:41:14 -07:00
utsname_sysctl.c
utsname.c
watch_queue.c watch_queue: Free the page array when watch_queue is dismantled 2022-04-02 10:37:39 -07:00
watchdog_hld.c
watchdog.c sched/isolation: Use single feature type while referring to housekeeping cpumask 2022-02-16 15:57:55 +01:00
workqueue_internal.h workqueue: Assign a color to barrier work items 2021-08-17 07:49:10 -10:00
workqueue.c Merge branch 'for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2022-03-23 12:40:51 -07:00