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BUG: KASAN: null-ptr-deref in smc_tcp_syn_recv_sock+0x92/0x420
Read of size 4 at addr 0000000000000ab4 by task syz.1.1463/13561

CPU: 0 UID: 0 PID: 13561 Comm: syz.1.1463 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <IRQ>
 dump_stack_lvl+0x189/0x250
 kasan_report+0x118/0x150
 kasan_check_range+0x2b0/0x2c0
 smc_tcp_syn_recv_sock+0x92/0x420
 tcp_check_req+0xf11/0x1800
 tcp_v4_rcv+0x1896/0x2f40
 ip_protocol_deliver_rcu+0x221/0x440
 ip_local_deliver_finish+0x3bb/0x6f0
 NF_HOOK+0x30c/0x3a0
 NF_HOOK+0x30c/0x3a0
 __netif_receive_skb+0x143/0x380
 process_backlog+0x60e/0x14f0
 __napi_poll+0xc7/0x360
 net_rx_action+0x707/0xe30
 handle_softirqs+0x286/0x870
 do_softirq+0xec/0x180
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x17d/0x1c0
 __dev_queue_xmit+0x1d79/0x3b50
 ip_finish_output2+0xd03/0x1160
 ip_output+0x2a1/0x3c0
 __ip_queue_xmit+0x1106/0x1b00
 __tcp_transmit_skb+0x2215/0x3680
 tcp_rcv_state_process+0x2a99/0x4140
 tcp_v4_do_rcv+0x3f2/0xce0
 __release_sock+0x21c/0x350
 release_sock+0x5f/0x1f0
 mptcp_connect+0x649/0x830
 __inet_stream_connect+0x2ae/0xe80
 inet_stream_connect+0x66/0xa0
 __sys_connect+0x316/0x440
 __x64_sys_connect+0x7a/0x90
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb745b8ebe9
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:00007fb746a4d038 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007fb745dc6180 RCX: 00007fb745b8ebe9
RDX: 0000000000000010 RSI: 0000200000000000 RDI: 000000000000000d
RBP: 00007fb745c11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb745dc6218 R14: 00007fb745dc6180 R15: 00007ffd40f682f8
 </TASK>
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