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Date:   Fri, 26 Jun 2020 10:09:15 -0700
Message-ID: <000000000000d411cf05a8ffc4a6@google.com>
Subject: WARNING: suspicious RCU usage in tipc_l2_send_msg
From:   syzbot <syzbot+47bbc6b678d317cccbe0@syzkaller.appspotmail.com>
To:     davem@davemloft.net, jmaloy@redhat.com, kuba@kernel.org,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        syzkaller-bugs@googlegroups.com,
        tipc-discussion@lists.sourceforge.net, ying.xue@windriver.com
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Sender: linux-kernel-owner@vger.kernel.org
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Hello,

syzbot found the following crash on:

HEAD commit:    b835a71e usbnet: smsc95xx: Fix use-after-free after removal
git tree:       net
console output: https://syzkaller.appspot.com/x/log.txt?x=1095a51d100000
kernel config:  https://syzkaller.appspot.com/x/.config?x=dcc6334acae363d4
dashboard link: https://syzkaller.appspot.com/bug?extid=47bbc6b678d317cccbe0
compiler:       gcc (GCC) 10.1.0-syz 20200507

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+47bbc6b678d317cccbe0@syzkaller.appspotmail.com

=============================
WARNING: suspicious RCU usage
5.8.0-rc1-syzkaller #0 Not tainted
-----------------------------
net/tipc/bearer.c:466 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
2 locks held by kworker/0:16/19143:
 #0: ffff8880a6901d38 ((wq_completion)cryptd){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff8880a6901d38 ((wq_completion)cryptd){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
 #0: ffff8880a6901d38 ((wq_completion)cryptd){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
 #0: ffff8880a6901d38 ((wq_completion)cryptd){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
 #0: ffff8880a6901d38 ((wq_completion)cryptd){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
 #0: ffff8880a6901d38 ((wq_completion)cryptd){+.+.}-{0:0}, at: process_one_work+0x82b/0x1670 kernel/workqueue.c:2240
 #1: ffffc90006f9fda8 ((work_completion)(&cpu_queue->work)){+.+.}-{0:0}, at: process_one_work+0x85f/0x1670 kernel/workqueue.c:2244

stack backtrace:
CPU: 0 PID: 19143 Comm: kworker/0:16 Not tainted 5.8.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: cryptd cryptd_queue_worker
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 tipc_l2_send_msg+0x354/0x420 net/tipc/bearer.c:466
 tipc_aead_encrypt_done+0x204/0x3a0 net/tipc/crypto.c:761
 cryptd_aead_crypt+0xe8/0x1d0 crypto/cryptd.c:739
 cryptd_queue_worker+0x118/0x1b0 crypto/cryptd.c:181
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293


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