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TCP recvmsg seq # bug 2: copied 923C9785, seq 923C974D, rcvnxt 923C974E, fl 40
WARNING: net/ipv4/tcp.c:2786 at tcp_recvmsg_locked+0x7cf/0x3600 net/ipv4/tcp.c:2784, CPU#0: syz-executor.0/6513
Modules linked in:
CPU: 0 UID: 0 PID: 6513 Comm: syz-executor.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:tcp_recvmsg_locked+0x820/0x3600 net/ipv4/tcp.c:2784
Code: 78 48 8b 54 24 58 0f 85 22 01 00 00 8b 12 4c 89 c0 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 3f 01 00 00 41 8b 08 44 8b 44 24 30 <67> 48 0f b9 3a e9 42 ff ff ff 89 f9 80 e1 07 80 c1 03 38 c1 0f 8c
RSP: 0018:ffffc9000bddf220 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00000000923c974e
RDX: 00000000923c974d RSI: 00000000923c9785 RDI: ffffffff8ffe6aa0
RBP: ffffc9000bddf5f0 R08: 0000000000000040 R09: ffffc9000bddfcb8
R10: ffffc9000bddf713 R11: fffff520017bbee4 R12: dffffc0000000000
R13: ffff888033caa728 R14: 1ffff1100edbc963 R15: dffffc0000000000
FS:  00007ffb1dbfe6c0(0000) GS:ffff8881256ed000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffb1e8e5820 CR3: 000000007d0cc000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 receive_fallback_to_copy net/ipv4/tcp.c:2030 [inline]
 tcp_zerocopy_receive+0x7fe/0x20e0 net/ipv4/tcp.c:2262
 do_tcp_getsockopt+0x208b/0x2950 net/ipv4/tcp.c:4796
 tcp_getsockopt+0x83/0x130 net/ipv4/tcp.c:4895
 do_sock_getsockopt+0x2d3/0x3f0 net/socket.c:2383
 __sys_getsockopt net/socket.c:2412 [inline]
 __do_sys_getsockopt net/socket.c:2419 [inline]
 __se_sys_getsockopt net/socket.c:2416 [inline]
 __x64_sys_getsockopt+0x1a4/0x240 net/socket.c:2416
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ffb1e86d079
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 d0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffb1dbfe0b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 00007ffb1e9abf80 RCX: 00007ffb1e86d079
RDX: 0000000000000023 RSI: 0000000000000006 RDI: 0000000000000003
RBP: 00007ffb1e8ce498 R08: 00000000200004c0 R09: 0000000000000000
R10: 0000000020000380 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007ffb1e9abf80 R15: 00007ffc7b2bdc68
 </TASK>
----------------
Code disassembly (best guess):
   0:	78 48                	js     0x4a
   2:	8b 54 24 58          	mov    0x58(%rsp),%edx
   6:	0f 85 22 01 00 00    	jne    0x12e
   c:	8b 12                	mov    (%rdx),%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 3f 01 00 00    	jne    0x161
  22:	41 8b 08             	mov    (%r8),%ecx
  25:	44 8b 44 24 30       	mov    0x30(%rsp),%r8d
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e9 42 ff ff ff       	jmp    0xffffff76
  34:	89 f9                	mov    %edi,%ecx
  36:	80 e1 07             	and    $0x7,%cl
  39:	80 c1 03             	add    $0x3,%cl
  3c:	38 c1                	cmp    %al,%cl
  3e:	0f                   	.byte 0xf
  3f:	8c                   	.byte 0x8c