Subject: Re: [syzbot] [net?] possible deadlock in hsr_dev_xmit (2)

From: syzbot <[email-masked]>
Date: Sun, 31 Mar 2024 23:11:27 -0700

syzbot has found a reproducer for the following issue on:

HEAD commit:    480e035fc4c7 Merge tag 'drm-next-2024-03-13' of https://gi..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=166a86e5180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1e5b814e91787669
dashboard link: https://syzkaller.appspot.com/bug?extid=fbf74291c3b7e753b481
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10526855180000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15e0f5c3180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5f73b6ef963d/disk-480e035f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/46c949396aad/vmlinux-480e035f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e3b4d0f5a5f8/bzImage-480e035f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

============================================
WARNING: possible recursive locking detected
6.8.0-syzkaller-08073-g480e035fc4c7 #0 Not tainted
--------------------------------------------
ksoftirqd/1/23 is trying to acquire lock:
ffff8880744d6da0 (&hsr->seqnr_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff8880744d6da0 (&hsr->seqnr_lock){+.-.}-{2:2}, at: hsr_dev_xmit+0x13e/0x1d0 net/hsr/hsr_device.c:229

but task is already holding lock:
ffff88802383ada0 (&hsr->seqnr_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
ffff88802383ada0 (&hsr->seqnr_lock){+.-.}-{2:2}, at: send_hsr_supervision_frame+0x276/0xad0 net/hsr/hsr_device.c:310

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&hsr->seqnr_lock);
  lock(&hsr->seqnr_lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

7 locks held by ksoftirqd/1/23:
 #0: ffffc900001d7a40 ((&hsr->announce_timer)){+.-.}-{0:0}, at: call_timer_fn+0xc0/0x600 kernel/time/timer.c:1789
 #1: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
 #1: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
 #1: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: hsr_announce+0xa3/0x370 net/hsr/hsr_device.c:387
 #2: ffff88802383ada0 (&hsr->seqnr_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline]
 #2: ffff88802383ada0 (&hsr->seqnr_lock){+.-.}-{2:2}, at: send_hsr_supervision_frame+0x276/0xad0 net/hsr/hsr_device.c:310
 #3: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
 #3: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
 #3: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: hsr_forward_skb+0xae/0x2400 net/hsr/hsr_forward.c:614
 #4: ffffffff8e132080 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
 #4: ffffffff8e132080 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:802 [inline]
 #4: ffffffff8e132080 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2c4/0x3b10 net/core/dev.c:4260
 #5: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
 #5: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
 #5: ffffffff8e132020 (rcu_read_lock){....}-{1:2}, at: br_dev_xmit+0x1b9/0x1a10 net/bridge/br_device.c:44
 #6: ffffffff8e132080 (rcu_read_lock_bh){....}-{1:2}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
 #6: ffffffff8e132080 (rcu_read_lock_bh){....}-{1:2}, at: rcu_read_lock_bh include/linux/rcupdate.h:802 [inline]
 #6: ffffffff8e132080 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x2c4/0x3b10 net/core/dev.c:4260

stack backtrace:
CPU: 1 PID: 23 Comm: ksoftirqd/1 Not tainted 6.8.0-syzkaller-08073-g480e035fc4c7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_deadlock kernel/locking/lockdep.c:3062 [inline]
 validate_chain+0x15c1/0x58e0 kernel/locking/lockdep.c:3856
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
 _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178
 spin_lock_bh include/linux/spinlock.h:356 [inline]
 hsr_dev_xmit+0x13e/0x1d0 net/hsr/hsr_device.c:229
 __netdev_start_xmit include/linux/netdevice.h:4903 [inline]
 netdev_start_xmit include/linux/netdevice.h:4917 [inline]
 xmit_one net/core/dev.c:3531 [inline]
 dev_hard_start_xmit+0x26a/0x790 net/core/dev.c:3547
 __dev_queue_xmit+0x19f4/0x3b10 net/core/dev.c:4335
 dev_queue_xmit include/linux/netdevice.h:3091 [inline]
 br_dev_queue_push_xmit+0x701/0x8d0 net/bridge/br_forward.c:53
 NF_HOOK+0x3a7/0x460 include/linux/netfilter.h:314
 br_forward_finish+0xe5/0x140 net/bridge/br_forward.c:66
 NF_HOOK+0x3a7/0x460 include/linux/netfilter.h:314
 __br_forward+0x489/0x660 net/bridge/br_forward.c:115
 deliver_clone net/bridge/br_forward.c:131 [inline]
 maybe_deliver+0xb3/0x150 net/bridge/br_forward.c:190
 br_flood+0x2e4/0x660 net/bridge/br_forward.c:236
 br_dev_xmit+0x118c/0x1a10
 __netdev_start_xmit include/linux/netdevice.h:4903 [inline]
 netdev_start_xmit include/linux/netdevice.h:4917 [inline]
 xmit_one net/core/dev.c:3531 [inline]
 dev_hard_start_xmit+0x26a/0x790 net/core/dev.c:3547
 __dev_queue_xmit+0x19f4/0x3b10 net/core/dev.c:4335
 dev_queue_xmit include/linux/netdevice.h:3091 [inline]
 hsr_xmit net/hsr/hsr_forward.c:380 [inline]
 hsr_forward_do net/hsr/hsr_forward.c:471 [inline]
 hsr_forward_skb+0x183f/0x2400 net/hsr/hsr_forward.c:619
 send_hsr_supervision_frame+0x548/0xad0 net/hsr/hsr_device.c:333
 hsr_announce+0x1a9/0x370 net/hsr/hsr_device.c:389
 call_timer_fn+0x17e/0x600 kernel/time/timer.c:1792
 expire_timers kernel/time/timer.c:1843 [inline]
 __run_timers kernel/time/timer.c:2408 [inline]
 __run_timer_base+0x66a/0x8e0 kernel/time/timer.c:2419
 run_timer_base kernel/time/timer.c:2428 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2438
 __do_softirq+0x2bc/0x943 kernel/softirq.c:554
 run_ksoftirqd+0xc5/0x130 kernel/softirq.c:924
 smpboot_thread_fn+0x544/0xa30 kernel/smpboot.c:164
 kthread+0x2f0/0x390 kernel/kthread.c:388
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
 </TASK>

---
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