syzbot


KCSAN: data-race in io_req_defer_failed / io_wq_free_work

Status: moderation: reported on 2024/05/06 05:59
Subsystems: io-uring
[Documentation on labels]
Reported-by: syzbot+ddbb83d8287549071f48@syzkaller.appspotmail.com
First crash: 43d, last: 16d

Sample crash report:
==================================================================
BUG: KCSAN: data-race in io_req_defer_failed / io_wq_free_work

write to 0xffff888110a23f48 of 8 bytes by task 17933 on cpu 0:
 io_req_defer_failed+0x6e/0x280 io_uring/io_uring.c:955
 io_req_task_cancel+0x21/0x30 io_uring/io_uring.c:1373
 io_handle_tw_list+0x1b9/0x200 io_uring/io_uring.c:1083
 tctx_task_work_run+0x6c/0x1b0 io_uring/io_uring.c:1155
 tctx_task_work+0x40/0x80 io_uring/io_uring.c:1173
 task_work_run+0x13a/0x1a0 kernel/task_work.c:180
 get_signal+0xeee/0x1080 kernel/signal.c:2681
 arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x59/0x130 kernel/entry/common.c:218
 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888110a23f48 of 8 bytes by task 17935 on cpu 1:
 req_ref_put_and_test io_uring/refs.h:22 [inline]
 io_wq_free_work+0x24/0x1b0 io_uring/io_uring.c:1791
 io_worker_handle_work+0x49f/0x9a0 io_uring/io-wq.c:600
 io_wq_worker+0x286/0x820 io_uring/io-wq.c:651
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x00000000000c0058 -> 0x00000000004c0118

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 17935 Comm: iou-wrk-17933 Not tainted 6.10.0-rc1-syzkaller-00296-g89be4025b0db #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/02 04:34 upstream 89be4025b0db 3113787f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in io_req_defer_failed / io_wq_free_work
2024/05/14 06:37 upstream 8815da98e06a fdb4c10c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in io_req_defer_failed / io_wq_free_work
2024/05/06 05:58 upstream b9158815de52 610f2a54 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in io_req_defer_failed / io_wq_free_work
* Struck through repros no longer work on HEAD.