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: 58d, last: 5d08h
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 282d 421d 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 132d 135d 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 200d 211d 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 0xffff888106116998 of 8 bytes by task 15168 on cpu 1:
 inode_set_ctime_to_ts+0x8f/0x190 fs/inode.c:2747
 inode_set_ctime_current+0x1e5/0x810 fs/inode.c:2811
 shmem_symlink+0x36b/0x3b0 mm/shmem.c:4140
 vfs_symlink+0x2c3/0x3c0 fs/namei.c:5523
 do_symlinkat+0xf0/0x460 fs/namei.c:5550
 __do_sys_symlink fs/namei.c:5576 [inline]
 __se_sys_symlink fs/namei.c:5574 [inline]
 __x64_sys_symlink+0x50/0x60 fs/namei.c:5574
 x64_sys_call+0x24a9/0x3000 arch/x86/include/generated/asm/syscalls_64.h:89
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888106116998 of 8 bytes by task 17584 on cpu 0:
 inode_get_ctime_sec include/linux/fs.h:1683 [inline]
 inode_get_ctime include/linux/fs.h:1693 [inline]
 generic_fillattr+0x1c4/0x340 fs/stat.c:101
 shmem_getattr+0x181/0x200 mm/shmem.c:1274
 vfs_getattr_nosec+0x146/0x1e0 fs/stat.c:213
 vfs_getattr+0x48/0x60 fs/stat.c:262
 vfs_statx_path+0x28/0x140 fs/stat.c:299
 vfs_statx+0xc4/0x170 fs/stat.c:356
 vfs_fstatat+0x115/0x170 fs/stat.c:375
 __do_sys_newfstatat fs/stat.c:542 [inline]
 __se_sys_newfstatat+0x55/0x3e0 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+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000697a17c6 -> 0x00000000697a17d5

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 17584 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/28 14:02 upstream 1f97d9dcf536 004c195c .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
2025/12/21 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.