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TCP recvmsg seq # bug 2: copied 4F7E5A48, seq 4F7E5A10, rcvnxt 4F7E5A11, fl 40
WARNING: net/ipv4/tcp.c:2776 at tcp_recvmsg_locked+0xa7f/0x28e0 net/ipv4/tcp.c:2776, CPU#1: syz.0.120/6588
Modules linked in:
CPU: 1 UID: 0 PID: 6588 Comm: syz.0.120 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+0xa8c/0x28e0 net/ipv4/tcp.c:2776
Code: 20 48 89 f0 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 be 1d 00 00 48 8d 3d d1 af f2 06 48 8b 04 24 44 8b 44 24 2c 89 da 8b 30 <67> 48 0f b9 3a e9 0e fa ff ff e8 b5 18 13 f8 49 8d 5e 60 be 08 00
RSP: 0018:ffffc900058c7450 EFLAGS: 00010246
RAX: ffff88803db2fbc0 RBX: 000000004f7e5a10 RCX: 000000004f7e5a11
RDX: 000000004f7e5a10 RSI: 000000004f7e5a48 RDI: ffffffff90e85240
RBP: 0000000000000001 R08: 0000000000000040 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
R13: ffff888036f56b70 R14: ffff888036f56b98 R15: ffff888036f56ba4
FS:  00007f5c7c4d96c0(0000) GS:ffff8880d6442000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000002000cf3d CR3: 000000004b545000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 receive_fallback_to_copy net/ipv4/tcp.c:2022 [inline]
 tcp_zerocopy_receive+0x14cc/0x2640 net/ipv4/tcp.c:2254
 do_tcp_getsockopt+0xc05/0x2a90 net/ipv4/tcp.c:4797
 tcp_getsockopt+0xe4/0x110 net/ipv4/tcp.c:4896
 do_sock_getsockopt+0x259/0x3d0 net/socket.c:2383
 __sys_getsockopt+0x148/0x260 net/socket.c:2412
 __do_sys_getsockopt net/socket.c:2419 [inline]
 __se_sys_getsockopt net/socket.c:2416 [inline]
 __x64_sys_getsockopt+0xbd/0x160 net/socket.c:2416
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5c7b787be9
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:00007f5c7c4d9028 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 00007f5c7b955f80 RCX: 00007f5c7b787be9
RDX: 0000000000000023 RSI: 0000000000000006 RDI: 0000000000000003
RBP: 00007f5c7b80b2bf R08: 00000000200004c0 R09: 0000000000000000
R10: 0000000020000380 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f5c7b955f80 R15: 00007fff0b6af668
 </TASK>
----------------
Code disassembly (best guess):
   0:	20 48 89             	and    %cl,-0x77(%rax)
   3:	f0 83 e0 07          	lock and $0x7,%eax
   7:	83 c0 03             	add    $0x3,%eax
   a:	38 d0                	cmp    %dl,%al
   c:	7c 08                	jl     0x16
   e:	84 d2                	test   %dl,%dl
  10:	0f 85 be 1d 00 00    	jne    0x1dd4
  16:	48 8d 3d d1 af f2 06 	lea    0x6f2afd1(%rip),%rdi        # 0x6f2afee
  1d:	48 8b 04 24          	mov    (%rsp),%rax
  21:	44 8b 44 24 2c       	mov    0x2c(%rsp),%r8d
  26:	89 da                	mov    %ebx,%edx
  28:	8b 30                	mov    (%rax),%esi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e9 0e fa ff ff       	jmp    0xfffffa42
  34:	e8 b5 18 13 f8       	call   0xf81318ee
  39:	49 8d 5e 60          	lea    0x60(%r14),%rbx
  3d:	be                   	.byte 0xbe
  3e:	08 00                	or     %al,(%rax)