[moderation] [io-uring?] KCSAN: data-race in io_sq_offload_create / prepare_creds

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 2988dfed8a5d Merge tag 'block-6.17-20250808' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=171ad434580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7136549ecfde7285
dashboard link: https://syzkaller.appspot.com/bug?extid=9c18f12c9eacb8eea6d4
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
CC: [ax...@kernel.dk io-u...@vger.kernel.org linux-...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8a6ecfb2a7ab/disk-2988dfed.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0927cc672327/vmlinux-2988dfed.xz
kernel image: https://storage.googleapis.com/syzbot-assets/665bc6e407e2/bzImage-2988dfed.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9c18f1...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in io_sq_offload_create / prepare_creds

write to 0xffff8881027aab28 of 4 bytes by task 3588 on cpu 1:
get_cred_many include/linux/cred.h:202 [inline]
get_cred include/linux/cred.h:218 [inline]
io_sq_offload_create+0x419/0x850 io_uring/sqpoll.c:449
io_uring_create+0x42e/0x610 io_uring/io_uring.c:3807
io_uring_setup io_uring/io_uring.c:3890 [inline]
__do_sys_io_uring_setup io_uring/io_uring.c:3924 [inline]
__se_sys_io_uring_setup+0x1f7/0x210 io_uring/io_uring.c:3915
__x64_sys_io_uring_setup+0x31/0x40 io_uring/io_uring.c:3915
x64_sys_call+0x2b21/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:426
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881027aaa80 of 184 bytes by task 3657 on cpu 0:
prepare_creds+0x6c/0x4c0 kernel/cred.c:219
install_session_keyring security/keys/process_keys.c:361 [inline]
lookup_user_key+0x263/0xd10 security/keys/process_keys.c:676
keyctl_revoke_key security/keys/keyctl.c:385 [inline]
__do_sys_keyctl security/keys/keyctl.c:1891 [inline]
__se_sys_keyctl+0x41d/0xb80 security/keys/keyctl.c:1874
__x64_sys_keyctl+0x67/0x80 security/keys/keyctl.c:1874
x64_sys_call+0x2f6d/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:251
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3657 Comm: syz.1.38 Not tainted 6.16.0-syzkaller-12245-g2988dfed8a5d #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.