============================================
WARNING: possible recursive locking detected
6.1.110-syzkaller #0 Not tainted
--------------------------------------------
syz.4.652/6183 is trying to acquire lock:
ffff8880278817b0 (k-slock-AF_INET){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff8880278817b0 (k-slock-AF_INET){+.-.}-{2:2}, at: sk_clone_lock+0x2c9/0xf20 net/core/sock.c:2260
but task is already holding lock:
ffff88807a3f5670 (k-slock-AF_INET){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff88807a3f5670 (k-slock-AF_INET){+.-.}-{2:2}, at: sk_clone_lock+0x2c9/0xf20 net/core/sock.c:2260
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.4.652/6183:
#0: ffff888027880cb0 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1748 [inline]
#0: ffff888027880cb0 (sk_lock-AF_INET){+.+.}-{0:0}, at: inet_stream_connect+0x4c/0xa0 net/ipv4/af_inet.c:740
#1: ffff88807a3f6f70 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1748 [inline]
#1: ffff88807a3f6f70 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: inet_stream_connect+0x4c/0xa0 net/ipv4/af_inet.c:740
#2: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#2: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#2: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: __ip_queue_xmit+0x54/0x1b60 net/ipv4/ip_output.c:467
#3: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#3: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#3: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x402/0x1330 net/ipv4/ip_output.c:221
#4: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#4: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#4: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: process_backlog+0x2c9/0x760 net/core/dev.c:5969
#5: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#5: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#5: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: ip_local_deliver_finish+0x1f3/0x580 net/ipv4/ip_input.c:232
#6: ffff88807a3f5670 (k-slock-AF_INET){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]
#6: ffff88807a3f5670 (k-slock-AF_INET){+.-.}-{2:2}, at: sk_clone_lock+0x2c9/0xf20 net/core/sock.c:2260
stack backtrace:
CPU: 1 PID: 6183 Comm: syz.4.652 Not tainted 6.1.110-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
print_deadlock_bug kernel/locking/lockdep.c:2983 [inline]
check_deadlock kernel/locking/lockdep.c:3026 [inline]
validate_chain+0x4711/0x5950 kernel/locking/lockdep.c:3812
__lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049
lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
sk_clone_lock+0x2c9/0xf20 net/core/sock.c:2260
mptcp_sk_clone_init+0xa0/0x1330 net/mptcp/protocol.c:3233
subflow_syn_recv_sock+0x950/0x1570 net/mptcp/subflow.c:764
tcp_check_req+0xf96/0x19c0 net/ipv4/tcp_minisocks.c:787
tcp_v4_rcv+0x1fd8/0x3250 net/ipv4/tcp_ipv4.c:2039
ip_protocol_deliver_rcu+0x381/0x740 net/ipv4/ip_input.c:205
ip_local_deliver_finish+0x304/0x580 net/ipv4/ip_input.c:233
NF_HOOK+0x39d/0x450 include/linux/netfilter.h:302
NF_HOOK+0x39d/0x450 include/linux/netfilter.h:302
__netif_receive_skb_one_core net/core/dev.c:5528 [inline]
__netif_receive_skb+0x1c6/0x530 net/core/dev.c:5642
process_backlog+0x381/0x760 net/core/dev.c:5970
__napi_poll+0xc7/0x470 net/core/dev.c:6537
napi_poll net/core/dev.c:6604 [inline]
net_rx_action+0x70f/0xeb0 net/core/dev.c:6718
handle_softirqs+0x2ee/0xa40 kernel/softirq.c:571
do_softirq+0x162/0x240 kernel/softirq.c:472
</IRQ>
<TASK>
__local_bh_enable_ip+0x1b1/0x1f0 kernel/softirq.c:396
local_bh_enable include/linux/bottom_half.h:33 [inline]
rcu_read_unlock_bh include/linux/rcupdate.h:861 [inline]
__dev_queue_xmit+0x1790/0x3cf0 net/core/dev.c:4320
dev_queue_xmit include/linux/netdevice.h:3021 [inline]
neigh_hh_output include/net/neighbour.h:528 [inline]
neigh_output include/net/neighbour.h:542 [inline]
ip_finish_output2+0xcfc/0x1330 net/ipv4/ip_output.c:228
dst_output include/net/dst.h:444 [inline]
ip_local_out net/ipv4/ip_output.c:126 [inline]
__ip_queue_xmit+0x11b1/0x1b60 net/ipv4/ip_output.c:532
__tcp_transmit_skb+0x1e33/0x33a0 net/ipv4/tcp_output.c:1403
tcp_rcv_synsent_state_process net/ipv4/tcp_input.c:6378 [inline]
tcp_rcv_state_process+0x2e28/0x4580 net/ipv4/tcp_input.c:6555
tcp_v4_do_rcv+0x729/0xb00 net/ipv4/tcp_ipv4.c:1703
sk_backlog_rcv include/net/sock.h:1117 [inline]
__release_sock+0x198/0x4b0 net/core/sock.c:2936
release_sock+0x5d/0x1c0 net/core/sock.c:3500
inet_stream_connect+0x84/0xa0 net/ipv4/af_inet.c:742
mptcp_connect+0x529/0x870 net/mptcp/protocol.c:3781
__inet_stream_connect+0x254/0xf10 net/ipv4/af_inet.c:670
inet_stream_connect+0x61/0xa0 net/ipv4/af_inet.c:741
__sys_connect_file net/socket.c:2006 [inline]
__sys_connect+0x2c9/0x300 net/socket.c:2023
__do_sys_connect net/socket.c:2033 [inline]
__se_sys_connect net/socket.c:2030 [inline]
__x64_sys_connect+0x76/0x80 net/socket.c:2030
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fde3bf7def9
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:00007fde3cdeb038 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007fde3c135f80 RCX: 00007fde3bf7def9
RDX: 0000000000000010 RSI: 0000000020000000 RDI: 0000000000000004
RBP: 00007fde3bff0b76 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fde3c135f80 R15: 00007fffed527788
</TASK>