x_tables: ip6_tables: rpfilter match: used from hooks OUTPUT, but only valid from PREROUTING ============================================ WARNING: possible recursive locking detected 6.1.90-syzkaller #0 Not tainted -------------------------------------------- syz-executor.0/6758 is trying to acquire lock: ffff0000db56f458 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff0000db56f458 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4304 [inline] ffff0000db56f458 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x164/0x548 net/sched/sch_generic.c:340 but task is already holding lock: ffff0000f8b5c8d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff0000f8b5c8d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4304 [inline] ffff0000f8b5c8d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x164/0x548 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 7 locks held by syz-executor.0/6758: #0: ffff800015a14ca0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #1: ffff800015a14d00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 #2: ffff0000ef7ac258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #2: ffff0000ef7ac258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:194 [inline] #2: ffff0000ef7ac258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3841 [inline] #2: ffff0000ef7ac258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x10b4/0x38d8 net/core/dev.c:4259 #3: ffff0000f8b5c8d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #3: ffff0000f8b5c8d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4304 [inline] #3: ffff0000f8b5c8d8 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x164/0x548 net/sched/sch_generic.c:340 #4: ffff800015a14ca0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:349 #5: ffff800015a14d00 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:349 #6: ffff0000daeaa258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:361 [inline] #6: ffff0000daeaa258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin include/net/sch_generic.h:194 [inline] #6: ffff0000daeaa258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_xmit_skb net/core/dev.c:3841 [inline] #6: ffff0000daeaa258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: __dev_queue_xmit+0x10b4/0x38d8 net/core/dev.c:4259 stack backtrace: CPU: 1 PID: 6758 Comm: syz-executor.0 Not tainted 6.1.90-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 Call trace: dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __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+0x6310/0x7680 kernel/locking/lockdep.c:5049 lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5662 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __netif_tx_lock include/linux/netdevice.h:4304 [inline] sch_direct_xmit+0x164/0x548 net/sched/sch_generic.c:340 __dev_xmit_skb net/core/dev.c:3854 [inline] __dev_queue_xmit+0x1658/0x38d8 net/core/dev.c:4259 dev_queue_xmit include/linux/netdevice.h:3021 [inline] neigh_resolve_output+0x558/0x658 net/core/neighbour.c:1563 neigh_output include/net/neighbour.h:544 [inline] ip_finish_output2+0xca0/0x11b8 net/ipv4/ip_output.c:228 __ip_finish_output+0x1b0/0x458 ip_finish_output+0x40/0x268 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:444 [inline] ip_local_out+0x120/0x160 net/ipv4/ip_output.c:126 iptunnel_xmit+0x40c/0x8ec net/ipv4/ip_tunnel_core.c:82 ip_tunnel_xmit+0x19a0/0x28bc net/ipv4/ip_tunnel.c:840 __gre_xmit net/ipv4/ip_gre.c:474 [inline] erspan_xmit+0xa00/0x14a8 net/ipv4/ip_gre.c:723 __netdev_start_xmit include/linux/netdevice.h:4853 [inline] netdev_start_xmit include/linux/netdevice.h:4867 [inline] xmit_one net/core/dev.c:3627 [inline] dev_hard_start_xmit+0x25c/0x9a4 net/core/dev.c:3643 sch_direct_xmit+0x234/0x548 net/sched/sch_generic.c:342 __dev_xmit_skb net/core/dev.c:3854 [inline] __dev_queue_xmit+0x1658/0x38d8 net/core/dev.c:4259 dev_queue_xmit include/linux/netdevice.h:3021 [inline] neigh_resolve_output+0x558/0x658 net/core/neighbour.c:1563 neigh_output include/net/neighbour.h:544 [inline] ip_finish_output2+0xca0/0x11b8 net/ipv4/ip_output.c:228 __ip_finish_output+0x1b0/0x458 ip_finish_output+0x40/0x268 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:444 [inline] ip_local_out net/ipv4/ip_output.c:126 [inline] ip_send_skb+0x134/0x2f8 net/ipv4/ip_output.c:1596 udp_send_skb+0x818/0x1418 net/ipv4/udp.c:988 udp_sendmsg+0x17a0/0x24f0 net/ipv4/udp.c:1276 udpv6_sendmsg+0x95c/0x28c8 net/ipv6/udp.c:1407 inet6_sendmsg+0xb4/0xd8 net/ipv6/af_inet6.c:670 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg net/socket.c:730 [inline] ____sys_sendmsg+0x55c/0x848 net/socket.c:2514 ___sys_sendmsg net/socket.c:2568 [inline] __sys_sendmmsg+0x318/0x7d8 net/socket.c:2654 __do_sys_sendmmsg net/socket.c:2683 [inline] __se_sys_sendmmsg net/socket.c:2680 [inline] __arm64_sys_sendmmsg+0xa0/0xbc net/socket.c:2680 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585