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Jens Axboe 0db4618e8f io_uring/msg_ring: fix uninitialized use of target_req->flags
syzbot reports that KMSAN complains that 'nr_tw' is an uninit-value
with the following report:

BUG: KMSAN: uninit-value in io_req_local_work_add io_uring/io_uring.c:1192 [inline]
BUG: KMSAN: uninit-value in io_req_task_work_add_remote+0x588/0x5d0 io_uring/io_uring.c:1240
 io_req_local_work_add io_uring/io_uring.c:1192 [inline]
 io_req_task_work_add_remote+0x588/0x5d0 io_uring/io_uring.c:1240
 io_msg_remote_post io_uring/msg_ring.c:102 [inline]
 io_msg_data_remote io_uring/msg_ring.c:133 [inline]
 io_msg_ring_data io_uring/msg_ring.c:152 [inline]
 io_msg_ring+0x1c38/0x1ef0 io_uring/msg_ring.c:305
 io_issue_sqe+0x383/0x22c0 io_uring/io_uring.c:1710
 io_queue_sqe io_uring/io_uring.c:1924 [inline]
 io_submit_sqe io_uring/io_uring.c:2180 [inline]
 io_submit_sqes+0x1259/0x2f20 io_uring/io_uring.c:2295
 __do_sys_io_uring_enter io_uring/io_uring.c:3205 [inline]
 __se_sys_io_uring_enter+0x40c/0x3ca0 io_uring/io_uring.c:3142
 __x64_sys_io_uring_enter+0x11f/0x1a0 io_uring/io_uring.c:3142
 x64_sys_call+0x2d82/0x3c10 arch/x86/include/generated/asm/syscalls_64.h:427
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

which is the following check:

if (nr_tw < nr_wait)
	return;

in io_req_local_work_add(). While nr_tw itself cannot be uninitialized,
it does depend on req->flags, which off the msg ring issue path can
indeed be uninitialized.

Fix this by always clearing the allocated 'req' fully if we can't grab
one from the cache itself.

Fixes: 50cf5f3842 ("io_uring/msg_ring: add an alloc cache for io_kiocb entries")
Reported-by: syzbot+82609b8937a4458106ca@syzkaller.appspotmail.com
Link: https://lore.kernel.org/io-uring/000000000000fd3d8d061dfc0e4a@google.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-07-25 08:41:35 -06:00
arch RISC-V Patches for the 6.11 Merge Window, Part 1 2024-07-20 09:11:27 -07:00
block SCSI misc on 20240718 2024-07-19 10:56:58 -07:00
certs kbuild: use $(src) instead of $(srctree)/$(src) for source directory 2024-05-10 04:34:52 +09:00
crypto crypto: testmgr - generate power-of-2 lengths more often 2024-07-13 11:50:28 +12:00
Documentation RISC-V Patches for the 6.11 Merge Window, Part 1 2024-07-20 09:11:27 -07:00
drivers RISC-V Patches for the 6.11 Merge Window, Part 1 2024-07-20 09:11:27 -07:00
fs for-6.11-tag 2024-07-19 14:34:52 -07:00
include io_uring: kill REQ_F_CANCEL_SEQ 2024-07-24 08:01:49 -06:00
init init/Kconfig: remove CONFIG_GCC_ASM_GOTO_OUTPUT_WORKAROUND 2024-07-18 10:33:14 -07:00
io_uring io_uring/msg_ring: fix uninitialized use of target_req->flags 2024-07-25 08:41:35 -06:00
ipc slab updates for 6.11 2024-07-18 15:08:12 -07:00
kernel pci-v6.11-changes 2024-07-19 19:03:18 -07:00
lib Char/Misc and other driver changes for 6.11-rc1 2024-07-19 15:55:08 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm NFS Client Updates for Linux 6.11 2024-07-18 17:17:30 -07:00
net Notably this includes fixes for a s390 build breakage. 2024-07-19 14:58:12 -07:00
rust slab updates for 6.11 2024-07-18 15:08:12 -07:00
samples Char/Misc and other driver changes for 6.11-rc1 2024-07-19 15:55:08 -07:00
scripts powerpc updates for 6.11 2024-07-19 21:00:33 -07:00
security This update includes the following changes: 2024-07-19 08:52:58 -07:00
sound Char/Misc and other driver changes for 6.11-rc1 2024-07-19 15:55:08 -07:00
tools RISC-V Patches for the 6.11 Merge Window, Part 1 2024-07-20 09:11:27 -07:00
usr kbuild: use $(src) instead of $(srctree)/$(src) for source directory 2024-05-10 04:34:52 +09:00
virt KVM fixes for 6.10 2024-06-21 08:03:55 -04:00
.clang-format Docs: Move clang-format from process/ to dev-tools/ 2024-06-26 16:36:00 -06:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: create a list of all built DTB files 2024-02-19 18:20:39 +09:00
.mailmap soc: dt updates for 6.11 2024-07-16 11:43:51 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS tracing: Update of MAINTAINERS and CREDITS file 2024-07-18 14:08:42 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS - added support for Realtek RTL9302C 2024-07-20 09:03:36 -07:00
Makefile asm-generic updates for 6.11 2024-07-16 12:09:03 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.