============================================ WARNING: possible recursive locking detected 6.11.0-syzkaller #0 Not tainted -------------------------------------------- syz.3.6750/20626 is trying to acquire lock: ffff88803f025418 (k-slock-AF_INET){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff88803f025418 (k-slock-AF_INET){+.-.}-{2:2}, at: sk_clone_lock+0x32b/0x12f0 net/core/sock.c:2328 but task is already holding lock: ffff8880527663d8 (k-slock-AF_INET){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff8880527663d8 (k-slock-AF_INET){+.-.}-{2:2}, at: sk_clone_lock+0x32b/0x12f0 net/core/sock.c:2328 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(k-slock-AF_INET); lock(k-slock-AF_INET); *** DEADLOCK *** May be due to missing lock nesting notation 7 locks held by syz.3.6750/20626: #0: ffff88803f0248d8 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1607 [inline] #0: ffff88803f0248d8 (sk_lock-AF_INET){+.+.}-{0:0}, at: inet_stream_connect+0x43/0xa0 net/ipv4/af_inet.c:749 #1: ffff88802fbd3f98 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1607 [inline] #1: ffff88802fbd3f98 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_connect+0x5aa/0xd20 net/mptcp/protocol.c:3762 #2: ffffffff8ddb9fe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:326 [inline] #2: ffffffff8ddb9fe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #2: ffffffff8ddb9fe0 (rcu_read_lock){....}-{1:2}, at: __ip_queue_xmit+0x72/0x1940 net/ipv4/ip_output.c:470 #3: ffffffff8ddb9fe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:326 [inline] #3: ffffffff8ddb9fe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #3: ffffffff8ddb9fe0 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x364/0x25e0 net/ipv4/ip_output.c:228 #4: ffffffff8ddb9fe0 (rcu_read_lock){....}-{1:2}, at: local_lock_release include/linux/local_lock_internal.h:38 [inline] #4: ffffffff8ddb9fe0 (rcu_read_lock){....}-{1:2}, at: process_backlog+0x3f1/0x15f0 net/core/dev.c:6106 #5: ffffffff8ddb9fe0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:326 [inline] #5: ffffffff8ddb9fe0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #5: ffffffff8ddb9fe0 (rcu_read_lock){....}-{1:2}, at: ip_local_deliver_finish+0x263/0x570 net/ipv4/ip_input.c:232 #6: ffff8880527663d8 (k-slock-AF_INET){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #6: ffff8880527663d8 (k-slock-AF_INET){+.-.}-{2:2}, at: sk_clone_lock+0x32b/0x12f0 net/core/sock.c:2328 stack backtrace: CPU: 2 UID: 0 PID: 20626 Comm: syz.3.6750 Not tainted 6.11.0-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:93 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:119 check_deadlock kernel/locking/lockdep.c:3061 [inline] validate_chain kernel/locking/lockdep.c:3855 [inline] __lock_acquire+0x2167/0x3cb0 kernel/locking/lockdep.c:5142 lock_acquire kernel/locking/lockdep.c:5759 [inline] lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5724 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] sk_clone_lock+0x32b/0x12f0 net/core/sock.c:2328 mptcp_sk_clone_init+0x30/0x1480 net/mptcp/protocol.c:3279 subflow_syn_recv_sock+0xe9c/0x1340 net/mptcp/subflow.c:874 tcp_check_req+0x9ab/0x1fb0 net/ipv4/tcp_minisocks.c:853 tcp_v4_rcv+0x1800/0x4390 net/ipv4/tcp_ipv4.c:2267 ip_protocol_deliver_rcu+0xba/0x4c0 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x316/0x570 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:314 [inline] NF_HOOK include/linux/netfilter.h:308 [inline] ip_local_deliver+0x18e/0x1f0 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:460 [inline] ip_rcv_finish net/ipv4/ip_input.c:449 [inline] NF_HOOK include/linux/netfilter.h:314 [inline] NF_HOOK include/linux/netfilter.h:308 [inline] ip_rcv+0x2c5/0x5d0 net/ipv4/ip_input.c:569 __netif_receive_skb_one_core+0x199/0x1e0 net/core/dev.c:5661 __netif_receive_skb+0x1d/0x160 net/core/dev.c:5775 process_backlog+0x443/0x15f0 net/core/dev.c:6108 __napi_poll.constprop.0+0xb7/0x550 net/core/dev.c:6772 napi_poll net/core/dev.c:6841 [inline] net_rx_action+0xa92/0x1010 net/core/dev.c:6963 handle_softirqs+0x216/0x8f0 kernel/softirq.c:554 do_softirq kernel/softirq.c:455 [inline] do_softirq+0xb2/0xf0 kernel/softirq.c:442 __local_bh_enable_ip+0x100/0x120 kernel/softirq.c:382 local_bh_enable include/linux/bottom_half.h:33 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:908 [inline] __dev_queue_xmit+0x882/0x4300 net/core/dev.c:4450 dev_queue_xmit include/linux/netdevice.h:3105 [inline] neigh_hh_output include/net/neighbour.h:526 [inline] neigh_output include/net/neighbour.h:540 [inline] ip_finish_output2+0x16fe/0x25e0 net/ipv4/ip_output.c:235 __ip_finish_output net/ipv4/ip_output.c:313 [inline] __ip_finish_output+0x49e/0x950 net/ipv4/ip_output.c:295 ip_finish_output+0x31/0x310 net/ipv4/ip_output.c:323 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip_output+0x13b/0x2a0 net/ipv4/ip_output.c:433 dst_output include/net/dst.h:450 [inline] ip_local_out+0x33e/0x4a0 net/ipv4/ip_output.c:129 __ip_queue_xmit+0x747/0x1940 net/ipv4/ip_output.c:535 __tcp_transmit_skb+0x2a4c/0x3dc0 net/ipv4/tcp_output.c:1466 __tcp_send_ack.part.0+0x390/0x720 net/ipv4/tcp_output.c:4268 __tcp_send_ack net/ipv4/tcp_output.c:4274 [inline] tcp_send_ack+0x82/0xa0 net/ipv4/tcp_output.c:4274 tcp_rcv_synsent_state_process net/ipv4/tcp_input.c:6542 [inline] tcp_rcv_state_process+0x4332/0x4f30 net/ipv4/tcp_input.c:6729 tcp_v4_do_rcv+0x1ad/0xa90 net/ipv4/tcp_ipv4.c:1934 sk_backlog_rcv include/net/sock.h:1111 [inline] __release_sock+0x31b/0x400 net/core/sock.c:3004 release_sock+0x5a/0x220 net/core/sock.c:3558 mptcp_connect+0xabd/0xd20 net/mptcp/protocol.c:3784 __inet_stream_connect+0x3c7/0x1020 net/ipv4/af_inet.c:679 inet_stream_connect+0x57/0xa0 net/ipv4/af_inet.c:750 __sys_connect_file+0x15f/0x1a0 net/socket.c:2061 __sys_connect+0x149/0x170 net/socket.c:2078 __do_sys_connect net/socket.c:2088 [inline] __se_sys_connect net/socket.c:2085 [inline] __x64_sys_connect+0x72/0xb0 net/socket.c:2085 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2a8fb7def9 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:00007f2a909c4038 EFLAGS: 00000246 ORIG_RAX: 000000000000002a RAX: ffffffffffffffda RBX: 00007f2a8fd35f80 RCX: 00007f2a8fb7def9 RDX: 0000000000000010 RSI: 0000000020000000 RDI: 0000000000000004 RBP: 00007f2a8fbf0b76 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f2a8fd35f80 R15: 00007ffc8b701798 vkms_vblank_simulate: vblank timer overrun