On Sat, Jun 27, 2020 at 1:25 AM syzbot <syzbot+47bbc6b678d317ccc...@syzkaller.appspotmail.com> wrote: > > 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+47bbc6b678d317ccc...@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 > Like in bearer.c, rcu_read_lock() is needed before calling b->media->send_msg() in tipc_aead_encrypt_done():
@@ -757,10 +757,12 @@ static void tipc_aead_encrypt_done(struct crypto_async_request *base, int err) switch (err) { case 0: this_cpu_inc(tx->stats->stat[STAT_ASYNC_OK]); + rcu_read_lock(); if (likely(test_bit(0, &b->up))) b->media->send_msg(net, skb, b, &tx_ctx->dst); else kfree_skb(skb); + rcu_read_unlock(); break; > > --- > This bug is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkal...@googlegroups.com. > > syzbot will keep track of this bug report. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.