syzbot


KCSAN: data-race in generic_fillattr / inode_set_ctime_to_ts (4)

Status: moderation: reported on 2025/12/05 22:17
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+f6f46f4f4282fb9ec53f@syzkaller.appspotmail.com
First crash: 53d, last: 37d
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in generic_fillattr / inode_set_ctime_to_ts fs 6 5 276d 416d 0/29 auto-obsoleted due to no activity on 2025/06/21 18:02
upstream KCSAN: data-race in generic_fillattr / inode_set_ctime_to_ts (3) fs 6 2 127d 129d 0/29 auto-obsoleted due to no activity on 2025/11/18 01:38
upstream KCSAN: data-race in generic_fillattr / inode_set_ctime_to_ts (2) fs 6 2 195d 206d 0/29 auto-obsoleted due to no activity on 2025/09/11 09:54

Sample crash report:
==================================================================
BUG: KCSAN: data-race in generic_fillattr / inode_set_ctime_to_ts

write to 0xffff88810485c6c8 of 4 bytes by task 11652 on cpu 0:
 inode_set_ctime_to_ts+0x84/0x170 fs/inode.c:2745
 __simple_unlink fs/libfs.c:791 [inline]
 simple_unlink+0x38/0x80 fs/libfs.c:806
 shmem_unlink+0x12d/0x140 mm/shmem.c:3991
 vfs_unlink+0x28b/0x440 fs/namei.c:5369
 do_unlinkat+0x1cd/0x4b0 fs/namei.c:5439
 __do_sys_unlink fs/namei.c:5474 [inline]
 __se_sys_unlink fs/namei.c:5472 [inline]
 __x64_sys_unlink+0x2e/0x40 fs/namei.c:5472
 x64_sys_call+0x2f48/0x3000 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810485c6c8 of 4 bytes by task 11491 on cpu 1:
 inode_get_ctime_nsec include/linux/fs.h:1688 [inline]
 inode_get_ctime include/linux/fs.h:1694 [inline]
 generic_fillattr+0x1d1/0x340 fs/stat.c:101
 shmem_getattr+0x181/0x200 mm/shmem.c:1274
 vfs_getattr_nosec+0x146/0x1e0 fs/stat.c:213
 vfs_getattr fs/stat.c:262 [inline]
 vfs_statx_path fs/stat.c:299 [inline]
 vfs_statx+0x113/0x390 fs/stat.c:356
 vfs_fstatat+0x115/0x170 fs/stat.c:375
 __do_sys_newfstatat fs/stat.c:542 [inline]
 __se_sys_newfstatat+0x55/0x260 fs/stat.c:536
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:536
 x64_sys_call+0x111f/0x3000 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x3976c1c5 -> 0x3aa7eec5

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 11491 Comm: udevd Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/21 21:44 upstream 9094662f6707 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in generic_fillattr / inode_set_ctime_to_ts
2025/12/13 12:23 upstream 9551a26f17d9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in generic_fillattr / inode_set_ctime_to_ts
2025/12/09 08:34 upstream cfd4039213e7 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in generic_fillattr / inode_set_ctime_to_ts
2025/12/05 22:16 upstream d1d36025a617 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in generic_fillattr / inode_set_ctime_to_ts
* Struck through repros no longer work on HEAD.