syzbot


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
[Documentation on labels]
Reported-by: syzbot+c886d58659d9942bf21f@syzkaller.appspotmail.com
First crash: 1d09h, last: 1d09h
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
90561fef-facb-4e9e-aa98-08c305242379 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 fc6e6eac62ee224ed1276afaf24df37313ad0a0c
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 563d 695d 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 732d 884d 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 65d 79d 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 0xffff88810b1aa940 of 4 bytes by task 13758 on cpu 0:
 inode_set_ctime_to_ts fs/inode.c:2772 [inline]
 inode_set_ctime_current+0x256/0x8c0 fs/inode.c:2835
 __simple_unlink fs/libfs.c:792 [inline]
 simple_unlink+0x2d/0x80 fs/libfs.c:807
 shmem_unlink+0x12d/0x140 mm/shmem.c:3981
 shmem_rename2+0x18e/0x310 mm/shmem.c:4062
 vfs_rename+0x97f/0xad0 fs/namei.c:6054
 filename_renameat2+0x3b6/0x6e0 fs/namei.c:6172
 __do_sys_rename fs/namei.c:6216 [inline]
 __se_sys_rename+0x4a/0x1c0 fs/namei.c:6212
 __x64_sys_rename+0x31/0x40 fs/namei.c:6212
 x64_sys_call+0x2b3/0x3020 arch/x86/include/generated/asm/syscalls_64.h:83
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810b1aa940 of 4 bytes by task 13781 on cpu 1:
 inode_get_ctime_nsec include/linux/fs.h:1690 [inline]
 inode_get_ctime include/linux/fs.h:1696 [inline]
 generic_fillattr+0x1d1/0x340 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+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x257765c0 -> 0x28725641

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 13781 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.