KCSAN: data-race in __d_instantiate / path_openat (3)

Status: auto-obsoleted due to no activity on 2026/06/25 07:42
Subsystems: fs
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+06faec728cc81c59b6e9@syzkaller.appspotmail.com
First crash: 125d, last: 109d
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
7ce74155 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KCSAN: data-race in __d_instantiate / path_openat (3) 2026/05/17 17:25 2026/05/17 17:25 2026/05/17 18:09 de5aae85
be13523f assessment-kcsan Benign: ✅ Confident: ✅ ❓ KCSAN: data-race in __d_instantiate / path_openat (3) 2026/04/14 22:21 2026/04/14 22:21 2026/04/14 22:42 c8d6f6d5
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in __d_instantiate / path_openat fs 6 1 441d 441d 0/29 auto-obsoleted due to no activity on 2025/07/28 17:11
upstream KCSAN: data-race in __d_instantiate / path_openat (2) fs 6 2 248d 289d 0/29 auto-obsoleted due to no activity on 2026/02/06 09:23

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __d_instantiate / path_openat

write to 0xffff88811b3323f0 of 8 bytes by task 12451 on cpu 1:
 __d_set_inode_and_type fs/dcache.c:407 [inline]
 __d_instantiate+0x1db/0x390 fs/dcache.c:2052
 d_make_persistent+0x72/0x110 fs/dcache.c:2870
 shmem_mknod+0x15f/0x170 mm/shmem.c:3881
 shmem_create+0x34/0x50 mm/shmem.c:3933
 lookup_open fs/namei.c:4511 [inline]
 open_last_lookups fs/namei.c:4611 [inline]
 path_openat+0xd75/0x2050 fs/namei.c:4855
 do_file_open+0x16c/0x290 fs/namei.c:4887
 do_sys_openat2+0x94/0x130 fs/open.c:1364
 do_sys_open fs/open.c:1370 [inline]
 __do_sys_openat fs/open.c:1386 [inline]
 __se_sys_openat fs/open.c:1381 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1381
 x64_sys_call+0x1e39/0x3020 arch/x86/include/generated/asm/syscalls_64.h:258
 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 0xffff88811b3323f0 of 8 bytes by task 12453 on cpu 0:
 lookup_fast_for_open fs/namei.c:4554 [inline]
 open_last_lookups fs/namei.c:4582 [inline]
 path_openat+0x464/0x2050 fs/namei.c:4855
 do_file_open+0x16c/0x290 fs/namei.c:4887
 do_sys_openat2+0x94/0x130 fs/open.c:1364
 do_sys_open fs/open.c:1370 [inline]
 __do_sys_openat fs/open.c:1386 [inline]
 __se_sys_openat fs/open.c:1381 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1381
 x64_sys_call+0x1e39/0x3020 arch/x86/include/generated/asm/syscalls_64.h:258
 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: 0x0000000000000000 -> 0xffff888105fa9348

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 12453 Comm: syz.6.2135 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 (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/30 07:41 upstream 57b8e2d666a3 005438fc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __d_instantiate / path_openat
2026/04/14 22:21 upstream d60bc1401583 362d1323 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __d_instantiate / path_openat
* Struck through repros no longer work on HEAD.