syzbot


KCSAN: data-race in prepare_kernel_cred / prepare_kernel_cred

Status: moderation: reported on 2025/05/13 06:08
Subsystems: lsm
[Documentation on labels]
Reported-by: syzbot+cd4a8fc88284fecb5e52@syzkaller.appspotmail.com
First crash: 97d, last: 39d

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

write to 0xffffffff86861120 of 4 bytes by task 3861 on cpu 1:
 get_cred_rcu include/linux/cred.h:228 [inline]
 get_task_cred kernel/cred.c:162 [inline]
 prepare_kernel_cred+0xf5/0x680 kernel/cred.c:593
 _request_firmware+0x446/0xbb0 drivers/base/firmware_loader/main.c:883
 request_firmware drivers/base/firmware_loader/main.c:966 [inline]
 cache_firmware drivers/base/firmware_loader/main.c:1304 [inline]
 __async_dev_cache_fw_image+0x66/0x160 drivers/base/firmware_loader/main.c:1418
 async_run_entry_fn+0x4f/0x180 kernel/async.c:129
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3321
 worker_thread+0x582/0x770 kernel/workqueue.c:3402
 kthread+0x489/0x510 kernel/kthread.c:464
 ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffffffff86861078 of 184 bytes by task 12 on cpu 0:
 prepare_kernel_cred+0x114/0x680 kernel/cred.c:595
 _request_firmware+0x446/0xbb0 drivers/base/firmware_loader/main.c:883
 request_firmware drivers/base/firmware_loader/main.c:966 [inline]
 cache_firmware drivers/base/firmware_loader/main.c:1304 [inline]
 __async_dev_cache_fw_image+0x66/0x160 drivers/base/firmware_loader/main.c:1418
 async_run_entry_fn+0x4f/0x180 kernel/async.c:129
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3321
 worker_thread+0x582/0x770 kernel/workqueue.c:3402
 kthread+0x489/0x510 kernel/kthread.c:464
 ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 12 Comm: kworker/u8:0 Not tainted 6.16.0-rc5-syzkaller-00038-g733923397fd9 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: async async_run_entry_fn
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/09 11:15 upstream 733923397fd9 f4e5e155 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in prepare_kernel_cred / prepare_kernel_cred
2025/07/02 14:42 upstream 66701750d556 bc80e4f0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in prepare_kernel_cred / prepare_kernel_cred
2025/06/28 19:02 upstream 67a993863163 fc9d8ee5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in prepare_kernel_cred / prepare_kernel_cred
2025/05/13 06:07 upstream e9565e23cd89 f6671af7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in prepare_kernel_cred / prepare_kernel_cred
* Struck through repros no longer work on HEAD.