syzbot


KCSAN: data-race in fill_mg_cmtime / simple_rename_timestamp (2)

Status: moderation: reported on 2025/03/24 15:11
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+3d0e00746449e812d008@syzkaller.appspotmail.com
First crash: 1d06h, last: 1d06h
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in fill_mg_cmtime / simple_rename_timestamp fs 3 64d 88d 0/28 auto-obsoleted due to no activity on 2025/03/17 15:26

Sample crash report:
==================================================================
BUG: KCSAN: data-race in fill_mg_cmtime / simple_rename_timestamp

write to 0xffff888104239834 of 4 bytes by task 8940 on cpu 0:
 inode_set_mtime_to_ts include/linux/fs.h:1708 [inline]
 simple_rename_timestamp+0x50/0xd0 fs/libfs.c:809
 shmem_rename2+0x284/0x2c0 mm/shmem.c:4088
 vfs_rename+0x875/0x9c0 fs/namei.c:5069
 do_renameat2+0x6a3/0xa70 fs/namei.c:5226
 __do_sys_rename fs/namei.c:5273 [inline]
 __se_sys_rename fs/namei.c:5271 [inline]
 __x64_sys_rename+0x58/0x70 fs/namei.c:5271
 x64_sys_call+0x2b1c/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:83
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888104239834 of 4 bytes by task 3486 on cpu 1:
 inode_get_mtime_nsec include/linux/fs.h:1694 [inline]
 inode_get_mtime include/linux/fs.h:1700 [inline]
 fill_mg_cmtime+0x58/0x280 fs/stat.c:55
 generic_fillattr+0x241/0x330 fs/stat.c:99
 shmem_getattr+0x17b/0x200 mm/shmem.c:1249
 vfs_getattr_nosec fs/stat.c:208 [inline]
 vfs_getattr+0x172/0x1b0 fs/stat.c:246
 vfs_statx_path fs/stat.c:283 [inline]
 vfs_statx+0x12d/0x320 fs/stat.c:349
 vfs_fstatat+0xe4/0x130 fs/stat.c:368
 __do_sys_newfstatat fs/stat.c:532 [inline]
 __se_sys_newfstatat+0x58/0x260 fs/stat.c:526
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:526
 x64_sys_call+0x236d/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x004e7d16 -> 0x0052745f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3486 Comm: udevd Not tainted 6.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================
udevd[3486]: inotify_add_watch(7, /dev/loop1p7, 10) failed: No such file or directory

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/03/24 15:10 upstream 38fec10eb60d 875573af .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in fill_mg_cmtime / simple_rename_timestamp
* Struck through repros no longer work on HEAD.