syzbot


KCSAN: data-race in lookup_user_key / prepare_creds

Status: moderation: reported on 2025/04/27 14:25
Subsystems: keyrings lsm
[Documentation on labels]
Reported-by: syzbot+6d08dc40c9fea86cb03a@syzkaller.appspotmail.com
First crash: 52d, last: 1d05h

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

write to 0xffff88812050d468 of 4 bytes by task 6173 on cpu 1:
 get_cred_many include/linux/cred.h:202 [inline]
 get_cred include/linux/cred.h:218 [inline]
 lookup_user_key+0xb6/0xd10 security/keys/process_keys.c:626
 __do_sys_add_key security/keys/keyctl.c:126 [inline]
 __se_sys_add_key+0x263/0x350 security/keys/keyctl.c:74
 __x64_sys_add_key+0x67/0x80 security/keys/keyctl.c:74
 x64_sys_call+0x1d0d/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:249
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88812050d3c0 of 184 bytes by task 6174 on cpu 0:
 prepare_creds+0x6c/0x4c0 kernel/cred.c:219
 install_thread_keyring security/keys/process_keys.c:249 [inline]
 lookup_user_key+0x12a/0xd10 security/keys/process_keys.c:635
 __do_sys_add_key security/keys/keyctl.c:126 [inline]
 __se_sys_add_key+0x263/0x350 security/keys/keyctl.c:74
 __x64_sys_add_key+0x67/0x80 security/keys/keyctl.c:74
 x64_sys_call+0x1d0d/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:249
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 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: 6174 Comm: syz.9.11547 Tainted: G        W           6.16.0-rc2-syzkaller-00045-g4663747812d1 #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/18 00:32 upstream 4663747812d1 e77fae15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in lookup_user_key / prepare_creds
2025/04/27 14:24 upstream 5bc1018675ec c6b4fb39 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in lookup_user_key / prepare_creds
* Struck through repros no longer work on HEAD.