syzbot


KCSAN: data-race in __queue_delayed_work / kvfree_call_rcu

Status: moderation: reported on 2024/10/01 22:51
Subsystems: bpf
[Documentation on labels]
Reported-by: syzbot+2c284690cd00b12125e1@syzkaller.appspotmail.com
First crash: 3d19h, last: 3d19h

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

read to 0xffff888237d1cce8 of 8 bytes by task 5281 on cpu 1:
 schedule_delayed_monitor_work kernel/rcu/tree.c:3520 [inline]
 kvfree_call_rcu+0x3b8/0x510 kernel/rcu/tree.c:3838
 trie_update_elem+0x47c/0x620 kernel/bpf/lpm_trie.c:441
 bpf_map_update_value+0x324/0x350 kernel/bpf/syscall.c:203
 generic_map_update_batch+0x401/0x520 kernel/bpf/syscall.c:1849
 bpf_map_do_batch+0x28c/0x3f0 kernel/bpf/syscall.c:5143
 __sys_bpf+0x2e5/0x7a0
 __do_sys_bpf kernel/bpf/syscall.c:5741 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5739 [inline]
 __x64_sys_bpf+0x43/0x50 kernel/bpf/syscall.c:5739
 x64_sys_call+0x2625/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:322
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff888237d1cce8 of 8 bytes by task 3521 on cpu 0:
 __queue_delayed_work+0xc8/0x1a0 kernel/workqueue.c:2513
 queue_delayed_work_on+0xdf/0x190 kernel/workqueue.c:2552
 queue_delayed_work include/linux/workqueue.h:677 [inline]
 schedule_delayed_monitor_work kernel/rcu/tree.c:3525 [inline]
 kfree_rcu_monitor+0x5e8/0x660 kernel/rcu/tree.c:3642
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3310
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3391
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3521 Comm: kworker/u8:9 Tainted: G        W          6.12.0-rc1-syzkaller-00031-ge32cde8d2bd7 #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: events_unbound kfree_rcu_monitor
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/10/01 22:50 upstream e32cde8d2bd7 ea2b66a6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __queue_delayed_work / kvfree_call_rcu
* Struck through repros no longer work on HEAD.