syzbot


upstream test error: KCSAN: data-race in dont_mount / lookup_fast

Status: moderation: reported on 2025/05/12 08:54
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+6d5740a1602559cb13b0@syzkaller.appspotmail.com
First crash: 7h21m, last: 7h21m

Sample crash report:
==================================================================
BUG: KCSAN: data-race in dont_mount / lookup_fast

read-write to 0xffff888106ddf240 of 4 bytes by task 3812 on cpu 1:
 dont_mount+0x2a/0x40 include/linux/dcache.h:375
 vfs_unlink+0x28f/0x420 fs/namei.c:4581
 do_unlinkat+0x28e/0x4c0 fs/namei.c:4643
 __do_sys_unlink fs/namei.c:4689 [inline]
 __se_sys_unlink fs/namei.c:4687 [inline]
 __x64_sys_unlink+0x2e/0x40 fs/namei.c:4687
 x64_sys_call+0x22a6/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:88
 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

read to 0xffff888106ddf240 of 4 bytes by task 3006 on cpu 0:
 d_revalidate fs/namei.c:928 [inline]
 lookup_fast+0xf0/0x320 fs/namei.c:1765
 walk_component+0x3f/0x220 fs/namei.c:2134
 lookup_last fs/namei.c:2636 [inline]
 path_lookupat+0xfe/0x2a0 fs/namei.c:2660
 filename_lookup+0x147/0x340 fs/namei.c:2689
 do_readlinkat+0x7d/0x320 fs/stat.c:568
 __do_sys_readlink fs/stat.c:605 [inline]
 __se_sys_readlink fs/stat.c:602 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:602
 x64_sys_call+0x2cf3/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:90
 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: 0x00300008 -> 0x00004008

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3006 Comm: udevd Not tainted 6.15.0-rc6-syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/12 08:53 upstream 82f2b0b97b36 77908e5f .config console log report [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce upstream test error: KCSAN: data-race in dont_mount / lookup_fast
* Struck through repros no longer work on HEAD.