syzbot


KCSAN: data-race in copy_creds / prepare_creds (2)

Status: moderation: reported on 2025/12/01 07:50
Subsystems: lsm
[Documentation on labels]
Reported-by: syzbot+a9c18b3cb9f026e801ba@syzkaller.appspotmail.com
First crash: 58d, last: 22d
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in copy_creds / prepare_creds lsm 6 3 116d 135d 0/29 auto-obsoleted due to no activity on 2025/11/29 06:24

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

write to 0xffff888162b7b468 of 4 bytes by task 22454 on cpu 0:
 get_cred_many include/linux/cred.h:219 [inline]
 copy_creds+0x78/0x340 kernel/cred.c:278
 copy_process+0x638/0x1ef0 kernel/fork.c:2086
 kernel_clone+0x16c/0x5c0 kernel/fork.c:2651
 __do_sys_clone3 kernel/fork.c:2953 [inline]
 __se_sys_clone3+0x1c2/0x200 kernel/fork.c:2932
 __x64_sys_clone3+0x31/0x40 kernel/fork.c:2932
 x64_sys_call+0x2c0f/0x3000 arch/x86/include/generated/asm/syscalls_64.h:436
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888162b7b3c0 of 184 bytes by task 22455 on cpu 1:
 prepare_creds+0x6e/0x550 kernel/cred.c:192
 __do_sys_capset kernel/capability.c:247 [inline]
 __se_sys_capset+0x2a3/0x450 kernel/capability.c:216
 __x64_sys_capset+0x31/0x40 kernel/capability.c:216
 x64_sys_call+0x2868/0x3000 arch/x86/include/generated/asm/syscalls_64.h:127
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 22455 Comm: syz.5.6094 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/07 02:50 upstream f0b9d8eb98df d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in copy_creds / prepare_creds
2026/01/02 13:47 upstream b69053dd3ffb d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in copy_creds / prepare_creds
2025/12/15 22:44 upstream 8f0b4cce4481 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in copy_creds / prepare_creds
2025/12/01 07:50 upstream 7d0a66e4bb90 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in copy_creds / prepare_creds
* Struck through repros no longer work on HEAD.