KCSAN: data-race in init_file / prepare_creds (3)

Status: moderation: reported on 2026/07/06 21:48
Subsystems: fs
Labels: race:benign prio:low
[Documentation on labels]
Reported-by: syzbot+557fdc985d6ac3831e14@syzkaller.appspotmail.com
First crash: 47d, last: 47d
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
c18ffeb9 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KCSAN: data-race in init_file / prepare_creds (3) 2026/07/08 01:55 2026/07/08 01:55 2026/07/08 02:32 93f57954
482c8da0 assessment-kcsan Benign: ✅ ❓ KCSAN: data-race in init_file / prepare_creds (3) 2026/07/06 21:48 2026/07/06 21:48 2026/07/06 23:08 93f57954
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in init_file / prepare_creds fs 6 1 450d 450d 0/29 auto-obsoleted due to no activity on 2025/07/25 02:49
upstream KCSAN: data-race in init_file / prepare_creds (2) fs prio:low 6 26 121d 392d 0/29 auto-obsoleted due to no activity on 2026/06/18 17:52

Sample crash report:
==================================================================
BUG: KCSAN: data-race in init_file / prepare_creds

write to 0xffff8881049530a8 of 4 bytes by task 7107 on cpu 1:
 get_cred_many include/linux/cred.h:222 [inline]
 get_cred include/linux/cred.h:238 [inline]
 init_file+0x2d/0x1b0 fs/file_table.c:183
 alloc_empty_file+0x85/0x1e0 fs/file_table.c:266
 alloc_file fs/file_table.c:396 [inline]
 alloc_file_pseudo+0x92/0x120 fs/file_table.c:427
 __anon_inode_getfile fs/anon_inodes.c:164 [inline]
 anon_inode_getfile+0xa0/0x120 fs/anon_inodes.c:202
 __do_sys_perf_event_open kernel/events/core.c:14179 [inline]
 __se_sys_perf_event_open+0xbf3/0x1250 kernel/events/core.c:13881
 __x64_sys_perf_event_open+0x67/0x80 kernel/events/core.c:13881
 x64_sys_call+0x2789/0x3020 arch/x86/include/generated/asm/syscalls_64.h:299
 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 0xffff888104953000 of 184 bytes by task 7106 on cpu 0:
 prepare_creds+0x71/0x550 kernel/cred.c:192
 __sys_setresgid+0x46c/0x570 kernel/sys.c:849
 __do_sys_setresgid kernel/sys.c:874 [inline]
 __se_sys_setresgid kernel/sys.c:872 [inline]
 __x64_sys_setresgid+0x3f/0x50 kernel/sys.c:872
 x64_sys_call+0x2aa1/0x3020 arch/x86/include/generated/asm/syscalls_64.h:120
 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 7106 Comm: syz.3.1049 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/06 21:48 upstream 8cdeaa50eae8 88b240e4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in init_file / prepare_creds
* Struck through repros no longer work on HEAD.