x_tables: ip6_tables: rpfilter match: used from hooks OUTPUT, but only valid from PREROUTING ============================================ WARNING: possible recursive locking detected 5.15.147-syzkaller #0 Not tainted -------------------------------------------- syz-executor.0/5557 is trying to acquire lock: ffff0001175e3898 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] ffff0001175e3898 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4429 [inline] ffff0001175e3898 (_xmit_ETHER#2){+.-.}-{2:2}, at: __dev_queue_xmit+0xf2c/0x2a6c net/core/dev.c:4244 but task is already holding lock: ffff0000c2a95898 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] ffff0000c2a95898 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4429 [inline] ffff0000c2a95898 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x15c/0x484 net/sched/sch_generic.c:340 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(_xmit_ETHER#2); lock(_xmit_ETHER#2); *** DEADLOCK *** May be due to missing lock nesting notation 6 locks held by syz-executor.0/5557: #0: ffff800014af1640 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:268 #1: ffff800014af1640 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:268 #2: ffff0000ce589258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline] #2: ffff0000ce589258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin+0x130/0x2bc include/net/sch_generic.h:173 #3: ffff0000c2a95898 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline] #3: ffff0000c2a95898 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4429 [inline] #3: ffff0000c2a95898 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x15c/0x484 net/sched/sch_generic.c:340 #4: ffff800014af1640 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:268 #5: ffff800014af1640 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:268 stack backtrace: CPU: 1 PID: 5557 Comm: syz-executor.0 Not tainted 5.15.147-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023 Call trace: dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106 dump_stack+0x1c/0x58 lib/dump_stack.c:113 __lock_acquire+0x62bc/0x7638 kernel/locking/lockdep.c:5012 lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline] _raw_spin_lock+0xb0/0x10c kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:363 [inline] __netif_tx_lock include/linux/netdevice.h:4429 [inline] __dev_queue_xmit+0xf2c/0x2a6c net/core/dev.c:4244 dev_queue_xmit+0x24/0x34 net/core/dev.c:4281 neigh_resolve_output+0x52c/0x5dc net/core/neighbour.c:1497 neigh_output include/net/neighbour.h:509 [inline] ip_finish_output2+0xd78/0x131c net/ipv4/ip_output.c:228 __ip_finish_output+0x1b0/0x458 ip_finish_output+0x40/0x218 net/ipv4/ip_output.c:316 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip_output+0x330/0x49c net/ipv4/ip_output.c:430 dst_output include/net/dst.h:443 [inline] ip_local_out+0x120/0x160 net/ipv4/ip_output.c:126 iptunnel_xmit+0x40c/0x8fc net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x1ad4/0x2358 net/ipv4/ip_tunnel.c:810 __gre_xmit net/ipv4/ip_gre.c:469 [inline] erspan_xmit+0x9cc/0x14cc net/ipv4/ip_gre.c:718 __netdev_start_xmit include/linux/netdevice.h:5019 [inline] netdev_start_xmit include/linux/netdevice.h:5033 [inline] xmit_one net/core/dev.c:3617 [inline] dev_hard_start_xmit+0x2bc/0x92c net/core/dev.c:3633 sch_direct_xmit+0x2e0/0x484 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3844 [inline] __dev_queue_xmit+0x14b4/0x2a6c net/core/dev.c:4213 dev_queue_xmit+0x24/0x34 net/core/dev.c:4281 neigh_resolve_output+0x52c/0x5dc net/core/neighbour.c:1497 neigh_output include/net/neighbour.h:509 [inline] ip_finish_output2+0xd78/0x131c net/ipv4/ip_output.c:228 __ip_finish_output+0x1b0/0x458 ip_finish_output+0x40/0x218 net/ipv4/ip_output.c:316 NF_HOOK_COND include/linux/netfilter.h:291 [inline] ip_output+0x330/0x49c net/ipv4/ip_output.c:430 dst_output include/net/dst.h:443 [inline] ip_local_out net/ipv4/ip_output.c:126 [inline] ip_send_skb+0x134/0x2f8 net/ipv4/ip_output.c:1581 udp_send_skb+0x6d0/0x11bc net/ipv4/udp.c:979 udp_sendmsg+0x17b0/0x252c net/ipv4/udp.c:1266 udpv6_sendmsg+0x668/0x2934 net/ipv6/udp.c:1392 inet6_sendmsg+0xb4/0xd8 net/ipv6/af_inet6.c:657 sock_sendmsg_nosec net/socket.c:704 [inline] __sock_sendmsg net/socket.c:716 [inline] ____sys_sendmsg+0x584/0x870 net/socket.c:2431 ___sys_sendmsg+0x214/0x294 net/socket.c:2485 __sys_sendmmsg+0x23c/0x648 net/socket.c:2571 __do_sys_sendmmsg net/socket.c:2600 [inline] __se_sys_sendmmsg net/socket.c:2597 [inline] __arm64_sys_sendmmsg+0xa0/0xbc net/socket.c:2597 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584