============================================
WARNING: possible recursive locking detected
syzkaller #0 Tainted: G L
--------------------------------------------
syz.1.4746/20040 is trying to acquire lock:
ffff88802bd915e0 (&br->multicast_lock){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:342 [inline]
ffff88802bd915e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_ip4_multicast_query net/bridge/br_multicast.c:3500 [inline]
ffff88802bd915e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_ipv4_rcv net/bridge/br_multicast.c:3914 [inline]
ffff88802bd915e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_rcv+0x2a6d/0x7640 net/bridge/br_multicast.c:4030
but task is already holding lock:
ffff8880586595e0 (&br->multicast_lock){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:342 [inline]
ffff8880586595e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_port_query_expired net/bridge/br_multicast.c:1903 [inline]
ffff8880586595e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_ip4_multicast_port_query_expired+0x68/0x380 net/bridge/br_multicast.c:1922
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&br->multicast_lock);
lock(&br->multicast_lock);
*** DEADLOCK ***
May be due to missing lock nesting notation
10 locks held by syz.1.4746/20040:
#0: ffffffff9032c0a0 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff9032c0a0 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#0: ffffffff9032c0a0 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
#1: ffffffff8fdd0f80 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
#1: ffffffff8fdd0f80 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
#1: ffffffff8fdd0f80 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x883/0x1bb0 net/core/rtnetlink.c:4109
#2: ffff88807c7ac530 (&idev->mc_lock){+.+.}-{4:4}, at: __ipv6_dev_mc_inc+0x4e/0xa50 net/ipv6/mcast.c:943
#3: ffffc90000a08ce0 ((&pmctx->ip4_own_query.timer)){+.-.}-{0:0}, at: call_timer_fn+0xd4/0x5e0 kernel/time/timer.c:1745
#4: ffff8880586595e0 (&br->multicast_lock){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:342 [inline]
#4: ffff8880586595e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_port_query_expired net/bridge/br_multicast.c:1903 [inline]
#4: ffff8880586595e0 (&br->multicast_lock){+.-.}-{3:3}, at: br_ip4_multicast_port_query_expired+0x68/0x380 net/bridge/br_multicast.c:1922
#5: ffffffff8e95cd00 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#5: ffffffff8e95cd00 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:891 [inline]
#5: ffffffff8e95cd00 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x2b6/0x3950 net/core/dev.c:4791
#6: ffffffff8e95cd00 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#6: ffffffff8e95cd00 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:891 [inline]
#6: ffffffff8e95cd00 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x2b6/0x3950 net/core/dev.c:4791
#7: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#7: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#7: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: bond_start_xmit+0xb4/0x1900 drivers/net/bonding/bond_main.c:5591
#8: ffffffff8e95cd00 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline]
#8: ffffffff8e95cd00 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:891 [inline]
#8: ffffffff8e95cd00 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x2b6/0x3950 net/core/dev.c:4791
#9: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#9: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#9: ffffffff8e95cca0 (rcu_read_lock){....}-{1:3}, at: br_dev_xmit+0x193/0x1990 net/bridge/br_device.c:52
stack backtrace:
CPU: 1 UID: 0 PID: 20040 Comm: syz.1.4746 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041
check_deadlock kernel/locking/lockdep.c:3093 [inline]
validate_chain kernel/locking/lockdep.c:3895 [inline]
__lock_acquire+0x253f/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
__raw_spin_lock include/linux/spinlock_api_smp.h:158 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:158
spin_lock include/linux/spinlock.h:342 [inline]
br_ip4_multicast_query net/bridge/br_multicast.c:3500 [inline]
br_multicast_ipv4_rcv net/bridge/br_multicast.c:3914 [inline]
br_multicast_rcv+0x2a6d/0x7640 net/bridge/br_multicast.c:4030
br_dev_xmit+0xb67/0x1990 net/bridge/br_device.c:98
__netdev_start_xmit include/linux/netdevice.h:5368 [inline]
netdev_start_xmit include/linux/netdevice.h:5377 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904
__dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4870
__bond_start_xmit drivers/net/bonding/bond_main.c:-1 [inline]
bond_start_xmit+0xd5c/0x1900 drivers/net/bonding/bond_main.c:5593
__netdev_start_xmit include/linux/netdevice.h:5368 [inline]
netdev_start_xmit include/linux/netdevice.h:5377 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904
__dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4870
dev_queue_xmit_accel include/linux/netdevice.h:3424 [inline]
macvlan_queue_xmit drivers/net/macvlan.c:571 [inline]
macvlan_start_xmit+0x3ba/0x600 drivers/net/macvlan.c:595
__netdev_start_xmit include/linux/netdevice.h:5368 [inline]
netdev_start_xmit include/linux/netdevice.h:5377 [inline]
xmit_one net/core/dev.c:3888 [inline]
dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904
__dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4870
dev_queue_xmit include/linux/netdevice.h:3418 [inline]
br_dev_queue_push_xmit+0x370/0x4b0 net/bridge/br_forward.c:53
NF_HOOK include/linux/netfilter.h:318 [inline]
__br_multicast_send_query+0x2f4a/0x4630 net/bridge/br_multicast.c:1807
br_multicast_send_query+0x509/0x6b0 net/bridge/br_multicast.c:1886
br_multicast_port_query_expired net/bridge/br_multicast.c:1911 [inline]
br_ip4_multicast_port_query_expired+0x2ab/0x380 net/bridge/br_multicast.c:1922
call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2374 [inline]
__run_timer_base+0x652/0x8b0 kernel/time/timer.c:2386
run_timer_base kernel/time/timer.c:2395 [inline]
run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405
handle_softirqs+0x22a/0x840 kernel/softirq.c:622
do_softirq+0x76/0xd0 kernel/softirq.c:523
__local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450
spin_unlock_bh include/linux/spinlock.h:396 [inline]
netif_addr_unlock_bh include/linux/netdevice.h:4962 [inline]
__dev_mc_add net/core/dev_addr_lists.c:1010 [inline]
dev_mc_add+0xd0/0x120 net/core/dev_addr_lists.c:1023
igmp6_group_added+0x234/0x820 net/ipv6/mcast.c:681
__ipv6_dev_mc_inc+0x897/0xa50 net/ipv6/mcast.c:972
br_ip6_multicast_join_snoopers net/bridge/br_multicast.c:4171 [inline]
br_multicast_join_snoopers+0x164/0x1c0 net/bridge/br_multicast.c:4182
br_multicast_toggle+0x444/0x450 net/bridge/br_multicast.c:4701
br_changelink+0xa4c/0x18d0 net/bridge/br_netlink.c:1433
rtnl_changelink net/core/rtnetlink.c:3760 [inline]
__rtnl_newlink net/core/rtnetlink.c:3973 [inline]
rtnl_newlink+0x1607/0x1bb0 net/core/rtnetlink.c:4110
rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6996
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
____sys_sendmsg+0x972/0x9f0 net/socket.c:2698
___sys_sendmsg+0x2a5/0x360 net/socket.c:2752
__sys_sendmsg net/socket.c:2784 [inline]
__do_sys_sendmsg net/socket.c:2789 [inline]
__se_sys_sendmsg net/socket.c:2787 [inline]
__x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc301b9ce59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc302a6e028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fc301e16090 RCX: 00007fc301b9ce59
RDX: 0000000000000000 RSI: 0000200000000240 RDI: 0000000000000004
RBP: 00007fc301c32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc301e16128 R14: 00007fc301e16090 R15: 00007fc301f3fa48