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

Status: moderation: reported on 2026/05/11 10:21
Subsystems: fs
Labels: race:benign prio:low
[Documentation on labels]
Reported-by: syzbot+c886d58659d9942bf21f@syzkaller.appspotmail.com
First crash: 94d, last: 22d
✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision
0bb10610 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ KCSAN: data-race in generic_fillattr / inode_set_ctime_current (4) 2026/05/30 09:48 2026/05/30 09:48 2026/05/30 10:25 6b4a8443
4ab1dfb6 assessment-security 💥 KCSAN: data-race in generic_fillattr / inode_set_ctime_current (4) 2026/05/14 09:25 2026/05/14 09:25 2026/05/14 09:28 6ccb967e
90561fef assessment-kcsan Benign: ✅ KCSAN: data-race in generic_fillattr / inode_set_ctime_current (4) 2026/05/11 10:20 2026/05/11 10:20 2026/05/11 10:43 fc6e6eac
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_current (2) fs 6 55 656d 788d 0/29 auto-obsoleted due to no activity on 2024/12/14 19:09
upstream KCSAN: data-race in generic_fillattr / inode_set_ctime_current fs 6 62 825d 977d 0/29 auto-obsoleted due to no activity on 2024/06/14 18:17
upstream KCSAN: data-race in generic_fillattr / inode_set_ctime_current (3) fs 6 2 158d 172d 0/29 auto-obsoleted due to no activity on 2026/05/02 22:36

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

write to 0xffff888103e28e90 of 4 bytes by task 3286 on cpu 0:
 inode_set_ctime_to_ts fs/inode.c:2837 [inline]
 inode_set_ctime_current+0x25b/0x8e0 fs/inode.c:2900
 shmem_symlink+0x34d/0x3a0 mm/shmem.c:4066
 vfs_symlink+0xfd/0x220 fs/namei.c:5660
 filename_symlinkat+0xe8/0x2b0 fs/namei.c:5685
 __do_sys_symlink fs/namei.c:5712 [inline]
 __se_sys_symlink+0x42/0x1b0 fs/namei.c:5708
 __x64_sys_symlink+0x31/0x40 fs/namei.c:5708
 x64_sys_call+0x2465/0x3020 arch/x86/include/generated/asm/syscalls_64.h:89
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888103e28e90 of 4 bytes by task 3288 on cpu 1:
 inode_get_ctime_nsec include/linux/fs.h:1685 [inline]
 inode_get_ctime include/linux/fs.h:1691 [inline]
 generic_fillattr+0x1d6/0x340 fs/stat.c:101
 shmem_getattr+0x181/0x200 mm/shmem.c:1302
 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+0x118/0x170 fs/stat.c:373
 __do_sys_newfstatat fs/stat.c:538 [inline]
 __se_sys_newfstatat+0x55/0x3e0 fs/stat.c:532
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:532
 x64_sys_call+0x2c64/0x3020 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x23f34a18 -> 0x2445f05e

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3288 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/21 22:03 upstream 248951ddc14d 7c5de9c3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in generic_fillattr / inode_set_ctime_current
2026/06/23 03:48 upstream 1dc18801be29 5a630be6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in generic_fillattr / inode_set_ctime_current
2026/06/20 02:02 upstream 5e2e14749c3d 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in generic_fillattr / inode_set_ctime_current
2026/05/11 10:20 upstream 5d6919055dec 845acb1c .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in generic_fillattr / inode_set_ctime_current
* Struck through repros no longer work on HEAD.