syzbot


KCSAN: data-race in __io_prep_rw / set_task_ioprio

Status: moderation: reported on 2025/07/18 17:56
Subsystems: block
[Documentation on labels]
Reported-by: syzbot+fd2c9b5e87d20a0dcafb@syzkaller.appspotmail.com
First crash: 17d, last: 17d

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __io_prep_rw / set_task_ioprio

write to 0xffff8881036e3988 of 8 bytes by task 18251 on cpu 1:
 set_task_ioprio+0x24f/0x270 block/blk-ioc.c:280
 __do_sys_ioprio_set block/ioprio.c:121 [inline]
 __se_sys_ioprio_set+0x250/0x5a0 block/ioprio.c:65
 __x64_sys_ioprio_set+0x43/0x50 block/ioprio.c:65
 x64_sys_call+0x1982/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:252
 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 0xffff8881036e3988 of 8 bytes by task 18240 on cpu 0:
 __get_task_ioprio include/linux/ioprio.h:59 [inline]
 get_current_ioprio include/linux/ioprio.h:83 [inline]
 __io_prep_rw+0x210/0x660 io_uring/rw.c:278
 io_prep_rw io_uring/rw.c:320 [inline]
 io_prep_rwv+0x33/0x230 io_uring/rw.c:342
 io_prep_writev+0x22/0x30 io_uring/rw.c:362
 io_init_req io_uring/io_uring.c:2139 [inline]
 io_submit_sqe io_uring/io_uring.c:2186 [inline]
 io_submit_sqes+0x5e5/0xfd0 io_uring/io_uring.c:2337
 __do_sys_io_uring_enter io_uring/io_uring.c:3404 [inline]
 __se_sys_io_uring_enter+0x1c1/0x1b70 io_uring/io_uring.c:3338
 __x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3338
 x64_sys_call+0x28c8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:427
 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

value changed: 0x0000000000000000 -> 0xffff8881170bafe0

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 18240 Comm: syz.2.5008 Not tainted 6.16.0-rc6-syzkaller-00121-g6832a9317eee #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/18 17:56 upstream 6832a9317eee 88248e14 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __io_prep_rw / set_task_ioprio
* Struck through repros no longer work on HEAD.