linux-kernel - [syzbot] [io-uring?] KCSAN: data-race in io_submit_sqes / io_uring_show

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Message-ID: <6811f6dc.050a0220.39e3a1.0d0e.GAE@google.com>
Date: Wed, 30 Apr 2025 03:09:32 -0700
From: syzbot <syzbot+3e77fd302e99f5af9394@...kaller.appspotmail.com>
To: asml.silence@...il.com, axboe@...nel.dk, io-uring@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [io-uring?] KCSAN: data-race in io_submit_sqes / io_uring_show_fdinfo

Hello,

syzbot found the following issue on:

HEAD commit:    ca91b9500108 Merge tag 'v6.15-rc4-ksmbd-server-fixes' of g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14a7d774580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6bd11c5d4ce102b4
dashboard link: https://syzkaller.appspot.com/bug?extid=3e77fd302e99f5af9394
compiler:       Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3a00fa544114/disk-ca91b950.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e82e624a4321/vmlinux-ca91b950.xz
kernel image: https://storage.googleapis.com/syzbot-assets/28e6034d0263/bzImage-ca91b950.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3e77fd302e99f5af9394@...kaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in io_submit_sqes / io_uring_show_fdinfo

read-write to 0xffff88810a2fe870 of 4 bytes by task 5625 on cpu 0:
 io_get_sqe io_uring/io_uring.c:2286 [inline]
 io_submit_sqes+0x235/0x1000 io_uring/io_uring.c:2339
 __io_sq_thread io_uring/sqpoll.c:189 [inline]
 io_sq_thread+0x778/0x1110 io_uring/sqpoll.c:312
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff88810a2fe870 of 4 bytes by task 5624 on cpu 1:
 io_uring_show_fdinfo+0x150/0xc40 io_uring/fdinfo.c:126
 seq_show+0x331/0x3b0 fs/proc/fd.c:68
 traverse+0x141/0x3a0 fs/seq_file.c:111
 seq_lseek+0xb5/0x170 fs/seq_file.c:323
 vfs_llseek fs/read_write.c:387 [inline]
 ksys_lseek fs/read_write.c:400 [inline]
 __do_sys_lseek fs/read_write.c:410 [inline]
 __se_sys_lseek fs/read_write.c:408 [inline]
 __x64_sys_lseek+0xe5/0x160 fs/read_write.c:408
 x64_sys_call+0x2d2a/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:9
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000e4d3 -> 0x0000e4f2

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5624 Comm: syz.0.732 Not tainted 6.15.0-rc4-syzkaller-00021-gca91b9500108 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
==================================================================


---
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