syzbot


KCSAN: data-race in do_epoll_wait / ep_done_scan (3)

Status: auto-closed as invalid on 2021/11/25 09:53
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 401d, last: 401d
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in do_epoll_wait / ep_done_scan 6 623d 677d 0/24 auto-closed as invalid on 2021/04/16 23:06
upstream KCSAN: data-race in do_epoll_wait / ep_done_scan (2) 1 553d 553d 0/24 auto-closed as invalid on 2021/06/26 18:27

Sample crash report:
==================================================================
BUG: KCSAN: data-race in do_epoll_wait / ep_done_scan

write to 0xffff8881028f77d8 of 8 bytes by task 482 on cpu 1:
 __list_add include/linux/list.h:70 [inline]
 list_add include/linux/list.h:86 [inline]
 ep_done_scan+0xab/0x270 fs/eventpoll.c:644
 ep_send_events fs/eventpoll.c:1716 [inline]
 ep_poll fs/eventpoll.c:1799 [inline]
 do_epoll_wait+0x9be/0xf10 fs/eventpoll.c:2227
 do_epoll_pwait fs/eventpoll.c:2261 [inline]
 __do_sys_epoll_pwait fs/eventpoll.c:2274 [inline]
 __se_sys_epoll_pwait+0x12b/0x240 fs/eventpoll.c:2268
 __x64_sys_epoll_pwait+0x74/0x80 fs/eventpoll.c:2268
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881028f77d8 of 8 bytes by task 484 on cpu 0:
 list_empty_careful include/linux/list.h:319 [inline]
 ep_events_available fs/eventpoll.c:374 [inline]
 ep_poll fs/eventpoll.c:1790 [inline]
 do_epoll_wait+0x26e/0xf10 fs/eventpoll.c:2227
 do_epoll_pwait fs/eventpoll.c:2261 [inline]
 __do_sys_epoll_pwait fs/eventpoll.c:2274 [inline]
 __se_sys_epoll_pwait+0x12b/0x240 fs/eventpoll.c:2268
 __x64_sys_epoll_pwait+0x74/0x80 fs/eventpoll.c:2268
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff8881028f77d0 -> 0xffff888100890c98

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 484 Comm: syz-fuzzer Not tainted 5.15.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-upstream-kcsan-gce 2021/10/21 09:43 upstream 2f111a6fd5b5 f111d03b .config log report info KCSAN: data-race in do_epoll_wait / ep_done_scan
* Struck through repros no longer work on HEAD.