Re: [syzbot] WARNING: suspicious RCU usage in find_inlist_lock

[Dmitry Vyukov]

On Sat, Apr 3, 2021 at 4:22 AM syzbot
<syzbot+b221933e5f9ad5b0e2fd@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    1e43c377 Merge tag 'xtensa-20210329' of git://github.com/j..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=114cdd4ad00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=78ef1d159159890
> dashboard link: https://syzkaller.appspot.com/bug?extid=b221933e5f9ad5b0e2fd
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b221933e5f9ad5b0e2fd@xxxxxxxxxxxxxxxxxxxxxxxxx

#syz dup: WARNING: suspicious RCU usage in getname_flags

> =============================
> WARNING: suspicious RCU usage
> 5.12.0-rc5-syzkaller #0 Not tainted
> -----------------------------
> kernel/sched/core.c:8294 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 syz-executor.1/8425.
>
> stack backtrace:
> CPU: 1 PID: 8425 Comm: syz-executor.1 Not tainted 5.12.0-rc5-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:8294
>  __mutex_lock_common kernel/locking/mutex.c:928 [inline]
>  __mutex_lock+0xa9/0x1120 kernel/locking/mutex.c:1096
>  find_inlist_lock_noload net/bridge/netfilter/ebtables.c:316 [inline]
>  find_inlist_lock.constprop.0+0x26/0x220 net/bridge/netfilter/ebtables.c:330
>  find_table_lock net/bridge/netfilter/ebtables.c:339 [inline]
>  do_ebt_get_ctl+0x208/0x790 net/bridge/netfilter/ebtables.c:2329
>  nf_getsockopt+0x72/0xd0 net/netfilter/nf_sockopt.c:116
>  ip_getsockopt net/ipv4/ip_sockglue.c:1777 [inline]
>  ip_getsockopt+0x164/0x1c0 net/ipv4/ip_sockglue.c:1756
>  tcp_getsockopt+0x86/0xd0 net/ipv4/tcp.c:4239
>  __sys_getsockopt+0x21f/0x5f0 net/socket.c:2161
>  __do_sys_getsockopt net/socket.c:2176 [inline]
>  __se_sys_getsockopt net/socket.c:2173 [inline]
>  __x64_sys_getsockopt+0xba/0x150 net/socket.c:2173
>  do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x467a6a
> Code: 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 37 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffe660d82f8 EFLAGS: 00000202 ORIG_RAX: 0000000000000037
> RAX: ffffffffffffffda RBX: 00000000005401a0 RCX: 0000000000467a6a
> RDX: 0000000000000081 RSI: 0000000000000000 RDI: 0000000000000003
> RBP: 0000000000000000 R08: 00007ffe660d831c R09: 00007ffe660d83a0
> R10: 00007ffe660d8320 R11: 0000000000000202 R12: 0000000000000003
> R13: 00007ffe660d8320 R14: 0000000000540128 R15: 00007ffe660d831c
>
>
> ---
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>
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