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TCP recvmsg seq # bug: copied DADAD6, seq DADB02, rcvnxt DADCE1, fl 0
WARNING: net/ipv4/tcp.c:2732 at tcp_recvmsg_locked+0x1d36/0x3800 net/ipv4/tcp.c:2729, CPU#0: syz.0.0/5324
Modules linked in:
CPU: 0 UID: 0 PID: 5324 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:tcp_recvmsg_locked+0x1d8d/0x3800 net/ipv4/tcp.c:2729
Code: 4c 8b 6c 24 70 0f 85 d1 0c 00 00 41 8b 16 4c 89 c0 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 ee 0c 00 00 41 8b 08 44 8b 44 24 48 <67> 48 0f b9 3a e9 e1 ec ff ff e8 b4 af 8b f7 bb ed ff ff ff eb 34
RSP: 0018:ffffc9000ed67640 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 1ffff11007d49023 RCX: 0000000000dadce1
RDX: 0000000000dadb02 RSI: 0000000000dadad6 RDI: ffffffff9067f2a0
RBP: ffffc9000ed67a10 R08: 0000000000000000 R09: ffffc9000ed67a7c
R10: dffffc0000000000 R11: fffffbfff20af687 R12: dffffc0000000000
R13: ffff888012d600e8 R14: ffff88803ea48118 R15: ffff88803ea480f0
FS:  00007f3a17e3b6c0(0000) GS:ffff88808c53e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000000135f CR3: 0000000012599000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 tcp_recvmsg+0x203/0x7f0 net/ipv4/tcp.c:2944
 sock_recvmsg_nosec net/socket.c:1128 [inline]
 sock_recvmsg+0x166/0x1e0 net/socket.c:1148
 sock_read_iter+0x22a/0x2f0 net/socket.c:1217
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x595/0xa80 fs/read_write.c:574
 ksys_read+0x150/0x270 fs/read_write.c:716
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3a16f9e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3a17e3afe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f3a17225fa0 RCX: 00007f3a16f9e0d9
RDX: 0000000000002020 RSI: 0000200000001900 RDI: 0000000000000005
RBP: 00007f3a17035024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3a17226038 R14: 00007f3a17225fa0 R15: 00007ffed61a6718
 </TASK>
----------------
Code disassembly (best guess):
   0:	4c 8b 6c 24 70       	mov    0x70(%rsp),%r13
   5:	0f 85 d1 0c 00 00    	jne    0xcdc
   b:	41 8b 16             	mov    (%r14),%edx
   e:	4c 89 c0             	mov    %r8,%rax
  11:	48 c1 e8 03          	shr    $0x3,%rax
  15:	42 0f b6 04 20       	movzbl (%rax,%r12,1),%eax
  1a:	84 c0                	test   %al,%al
  1c:	0f 85 ee 0c 00 00    	jne    0xd10
  22:	41 8b 08             	mov    (%r8),%ecx
  25:	44 8b 44 24 48       	mov    0x48(%rsp),%r8d
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e9 e1 ec ff ff       	jmp    0xffffed15
  34:	e8 b4 af 8b f7       	call   0xf78bafed
  39:	bb ed ff ff ff       	mov    $0xffffffed,%ebx
  3e:	eb 34                	jmp    0x74