============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.4.1606/10762 is trying to acquire lock: ffff88807deecf30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffff88807deecf30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: hsr_dev_xmit+0x237/0x360 net/hsr/hsr_device.c:235 but task is already holding lock: ffff888030f84f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffff888030f84f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: send_hsr_supervision_frame+0x380/0xcb0 net/hsr/hsr_device.c:330 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 9 locks held by syz.4.1606/10762: #0: ffff88806dd27ac8 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:980 [inline] #0: ffff88806dd27ac8 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: __sock_release net/socket.c:661 [inline] #0: ffff88806dd27ac8 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: sock_close+0x9b/0x240 net/socket.c:1455 #1: ffffc90000007be0 ((&hsr->announce_timer)){+.-.}-{0:0}, at: call_timer_fn+0xbe/0x5f0 kernel/time/timer.c:1744 #2: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #2: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #2: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: hsr_announce+0x83/0x360 net/hsr/hsr_device.c:419 #3: ffff888030f84f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] #3: ffff888030f84f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: send_hsr_supervision_frame+0x380/0xcb0 net/hsr/hsr_device.c:330 #4: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #4: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #4: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: hsr_forward_skb+0x9e/0x2860 net/hsr/hsr_forward.c:736 #5: ffffffff8df3d700 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #5: ffffffff8df3d700 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:918 [inline] #5: ffffffff8df3d700 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x284/0x3740 net/core/dev.c:4736 #6: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #6: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #6: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: br_dev_xmit+0x185/0x1840 net/bridge/br_device.c:52 #7: ffffffff8df3d700 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #7: ffffffff8df3d700 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:918 [inline] #7: ffffffff8df3d700 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x284/0x3740 net/core/dev.c:4736 #8: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #8: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #8: ffffffff8df3d6a0 (rcu_read_lock){....}-{1:3}, at: hsr_dev_xmit+0x2d/0x360 net/hsr/hsr_device.c:229 stack backtrace: CPU: 0 UID: 0 PID: 10762 Comm: syz.4.1606 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_deadlock_bug+0x28b/0x2a0 kernel/locking/lockdep.c:3041 check_deadlock kernel/locking/lockdep.c:3093 [inline] validate_chain+0x1a3f/0x2140 kernel/locking/lockdep.c:3895 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x36/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] hsr_dev_xmit+0x237/0x360 net/hsr/hsr_device.c:235 __netdev_start_xmit include/linux/netdevice.h:5259 [inline] netdev_start_xmit include/linux/netdevice.h:5268 [inline] xmit_one net/core/dev.c:3853 [inline] dev_hard_start_xmit+0x2d7/0x830 net/core/dev.c:3869 __dev_queue_xmit+0x172a/0x3740 net/core/dev.c:4811 dev_queue_xmit include/linux/netdevice.h:3368 [inline] br_dev_queue_push_xmit+0x6c5/0x890 net/bridge/br_forward.c:53 NF_HOOK+0x320/0x3c0 include/linux/netfilter.h:318 br_forward_finish+0xd3/0x130 net/bridge/br_forward.c:66 NF_HOOK+0x320/0x3c0 include/linux/netfilter.h:318 __br_forward+0x41e/0x600 net/bridge/br_forward.c:115 deliver_clone net/bridge/br_forward.c:131 [inline] maybe_deliver+0xb5/0x160 net/bridge/br_forward.c:191 br_flood+0x31a/0x6a0 net/bridge/br_forward.c:238 br_dev_xmit+0x11b3/0x1840 net/bridge/br_device.c:108 __netdev_start_xmit include/linux/netdevice.h:5259 [inline] netdev_start_xmit include/linux/netdevice.h:5268 [inline] xmit_one net/core/dev.c:3853 [inline] dev_hard_start_xmit+0x2d7/0x830 net/core/dev.c:3869 __dev_queue_xmit+0x172a/0x3740 net/core/dev.c:4811 dev_queue_xmit include/linux/netdevice.h:3368 [inline] hsr_xmit net/hsr/hsr_forward.c:438 [inline] hsr_forward_do net/hsr/hsr_forward.c:579 [inline] hsr_forward_skb+0x158b/0x2860 net/hsr/hsr_forward.c:741 send_hsr_supervision_frame+0x731/0xcb0 net/hsr/hsr_device.c:364 hsr_announce+0x1d5/0x360 net/hsr/hsr_device.c:421 call_timer_fn+0x17e/0x5f0 kernel/time/timer.c:1747 expire_timers kernel/time/timer.c:1798 [inline] __run_timers kernel/time/timer.c:2372 [inline] __run_timer_base+0x61a/0x860 kernel/time/timer.c:2384 run_timer_base kernel/time/timer.c:2393 [inline] run_timer_softirq+0xb7/0x180 kernel/time/timer.c:2403 handle_softirqs+0x286/0x870 kernel/softirq.c:622 __do_softirq kernel/softirq.c:656 [inline] invoke_softirq kernel/softirq.c:496 [inline] __irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:723 irq_exit_rcu+0x9/0x30 kernel/softirq.c:739 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1052 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:arch_stack_walk+0xaf/0x150 arch/x86/kernel/stacktrace.c:18 Code: 00 00 48 c7 45 b8 00 00 00 00 48 c7 45 b0 00 00 00 00 48 c7 45 a8 00 00 00 00 48 c7 45 a0 00 00 00 00 48 c7 45 98 00 00 00 00 <48> c7 45 90 00 00 00 00 48 c7 45 88 00 00 00 00 48 c7 45 80 00 00 RSP: 0018:ffffc9000c04f6c8 EFLAGS: 00000246 RAX: ffff888020339e40 RBX: ffffc9000c04f780 RCX: ffffc9000c04f750 RDX: ffff888020339e40 RSI: ffffc9000c04f780 RDI: ffffffff81ac2ea0 RBP: ffffc9000c04f750 R08: dffffc0000000000 R09: 0000000000000000 R10: ffffc9000c04f810 R11: fffffbfff1ef9faf R12: ffff888020339e40 R13: 0000000000000000 R14: ffffffff81ac2ea0 R15: 0000000000000000 stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:56 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:77 __kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587 kasan_save_free_info mm/kasan/kasan.h:406 [inline] poison_slab_object mm/kasan/common.c:252 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284 kasan_slab_free include/linux/kasan.h:234 [inline] slab_free_hook mm/slub.c:2543 [inline] slab_free mm/slub.c:6638 [inline] kmem_cache_free+0x19b/0x690 mm/slub.c:6748 kfree_skb_reason include/linux/skbuff.h:1322 [inline] __skb_queue_purge_reason include/linux/skbuff.h:3425 [inline] skb_queue_purge_reason+0x2c8/0x360 net/core/skbuff.c:3970 skb_queue_purge include/linux/skbuff.h:3438 [inline] packet_release+0xb29/0xcb0 net/packet/af_packet.c:3177 __sock_release net/socket.c:662 [inline] sock_close+0xc3/0x240 net/socket.c:1455 __fput+0x44c/0xa70 fs/file_table.c:468 task_work_run+0x1d4/0x260 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xe9/0x130 kernel/entry/common.c:43 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline] do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f150358f6c9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fffcaf21e48 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 000000000003345e RCX: 00007f150358f6c9 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007f15037e7da0 R08: 0000000000000001 R09: 0000001acaf2213f R10: 0000001b2fe20000 R11: 0000000000000246 R12: 00007f15037e5fac R13: 00007f15037e5fa0 R14: ffffffffffffffff R15: 00007fffcaf21f60 ---------------- Code disassembly (best guess): 0: 00 00 add %al,(%rax) 2: 48 c7 45 b8 00 00 00 movq $0x0,-0x48(%rbp) 9: 00 a: 48 c7 45 b0 00 00 00 movq $0x0,-0x50(%rbp) 11: 00 12: 48 c7 45 a8 00 00 00 movq $0x0,-0x58(%rbp) 19: 00 1a: 48 c7 45 a0 00 00 00 movq $0x0,-0x60(%rbp) 21: 00 22: 48 c7 45 98 00 00 00 movq $0x0,-0x68(%rbp) 29: 00 * 2a: 48 c7 45 90 00 00 00 movq $0x0,-0x70(%rbp) <-- trapping instruction 31: 00 32: 48 c7 45 88 00 00 00 movq $0x0,-0x78(%rbp) 39: 00 3a: 48 rex.W 3b: c7 .byte 0xc7 3c: 45 80 00 00 rex.RB addb $0x0,(%r8)