syzbot


WARNING: suspicious RCU usage in __fput

Status: fixed on 2021/11/10 00:50
Reported-by: syzbot+@syzkaller.appspotmail.com
Fix commit: 3066820034b5 rcu: Reject RCU_LOCKDEP_WARN() false positives
First crash: 486d, last: 486d

Sample crash report:
=============================
WARNING: suspicious RCU usage
5.13.0-rc3-syzkaller #0 Not tainted
-----------------------------
kernel/sched/core.c:8304 Illegal context switch in RCU-sched read-side critical section!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 0
no locks held by systemd-udevd/4849.

stack backtrace:
CPU: 1 PID: 4849 Comm: systemd-udevd Not tainted 5.13.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 ___might_sleep+0x266/0x2c0 kernel/sched/core.c:8304
 __fput+0xf9/0x920 fs/file_table.c:264
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x272/0x280 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:57
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f664dd4ba07
Code: 2e 00 f7 d8 bf ff ff ff ff 64 89 02 eb d0 0f 1f 44 00 00 48 85 ff 74 3b 53 8b 1f e8 3b bf f6 ff 48 63 fb b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 09 5b c3 0f 1f 80 00 00 00 00 48 8b 15 59 54
RSP: 002b:00007fffefe75b00 EFLAGS: 00000202
 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 000000000000000f RCX: 00007f664dd4ba07
RDX: 00007f664e031b58 RSI: 0000000000000000 RDI: 000000000000000f
RBP: 00007f664ef01710 R08: 000055c17cd49fe0 R09: 0000000000008040
R10: 00007f664e031b58 R11: 0000000000000202 R12: 0000000000000000
R13: 000055c17cd31c60 R14: 00000000000000ff R15: 000055c17cd31c60

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-selinux-root 2021/05/26 02:05 upstream a050a6d2b7e8 93d3a9f6 .config log report info WARNING: suspicious RCU usage in __fput
* Struck through repros no longer work on HEAD.