BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 10cb6f067 P4D 10cb6f067 PUD 10d320067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP
CPU: 1 PID: 5066 Comm: syz-executor.0 Not tainted 6.6.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023
RIP: 0010:ccid_hc_tx_send_packet net/dccp/ccid.h:166 [inline]
RIP: 0010:dccp_write_xmit+0x31/0x110 net/dccp/output.c:356
Code: 89 fc 55 53 e8 60 3a fc fd 4c 89 e7 e8 28 45 00 00 48 85 c0 48 89 c5 0f 84 b1 00 00 00 e8 47 3a fc fd 49 8b 84 24 e8 08 00 00 <48> 8b 00 48 8b 98 b0 00 00 00 48 85 db 0f 84 9a 00 00 00 e8 27 3a
RSP: 0018:ffffc90005683b30 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff8881033cd7c0 RCX: 0000000000000000
RDX: ffff888106f2b680 RSI: ffffffff8330dbe9 RDI: ffff8881033cd7c0
RBP: ffff8881073b1a00 R08: 000000000008067b R09: ffff888106f2c060
R10: 0000000000080000 R11: 0000000000000001 R12: ffff8881033cd7c0
R13: 0000000000000000 R14: ffffc90005683e00 R15: ffff8881073b1a00
FS:  00007fe2d919f6c0(0000) GS:ffff888237d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000010fb4d000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 dccp_sendmsg+0x589/0x5d0 net/dccp/proto.c:801
 inet_sendmsg+0x49/0x70 net/ipv4/af_inet.c:846
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x52/0xa0 net/socket.c:745
 ____sys_sendmsg+0x151/0x3e0 net/socket.c:2558
 ___sys_sendmsg+0xc9/0x130 net/socket.c:2612
 __sys_sendmmsg+0x12e/0x330 net/socket.c:2698
 __do_sys_sendmmsg net/socket.c:2727 [inline]
 __se_sys_sendmmsg net/socket.c:2724 [inline]
 __x64_sys_sendmmsg+0x25/0x30 net/socket.c:2724
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fe2d847cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe2d919f0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007fe2d859c050 RCX: 00007fe2d847cae9
RDX: 0400000000000239 RSI: 0000000020002980 RDI: 0000000000000006
RBP: 00007fe2d84c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007fe2d859c050 R15: 00007ffec15efb18
 </TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:ccid_hc_tx_send_packet net/dccp/ccid.h:166 [inline]
RIP: 0010:dccp_write_xmit+0x31/0x110 net/dccp/output.c:356
Code: 89 fc 55 53 e8 60 3a fc fd 4c 89 e7 e8 28 45 00 00 48 85 c0 48 89 c5 0f 84 b1 00 00 00 e8 47 3a fc fd 49 8b 84 24 e8 08 00 00 <48> 8b 00 48 8b 98 b0 00 00 00 48 85 db 0f 84 9a 00 00 00 e8 27 3a
RSP: 0018:ffffc90005683b30 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff8881033cd7c0 RCX: 0000000000000000
RDX: ffff888106f2b680 RSI: ffffffff8330dbe9 RDI: ffff8881033cd7c0
RBP: ffff8881073b1a00 R08: 000000000008067b R09: ffff888106f2c060
R10: 0000000000080000 R11: 0000000000000001 R12: ffff8881033cd7c0
R13: 0000000000000000 R14: ffffc90005683e00 R15: ffff8881073b1a00
FS:  00007fe2d919f6c0(0000) GS:ffff888237d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000010fb4d000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	89 fc                	mov    %edi,%esp
   2:	55                   	push   %rbp
   3:	53                   	push   %rbx
   4:	e8 60 3a fc fd       	call   0xfdfc3a69
   9:	4c 89 e7             	mov    %r12,%rdi
   c:	e8 28 45 00 00       	call   0x4539
  11:	48 85 c0             	test   %rax,%rax
  14:	48 89 c5             	mov    %rax,%rbp
  17:	0f 84 b1 00 00 00    	je     0xce
  1d:	e8 47 3a fc fd       	call   0xfdfc3a69
  22:	49 8b 84 24 e8 08 00 	mov    0x8e8(%r12),%rax
  29:	00
* 2a:	48 8b 00             	mov    (%rax),%rax <-- trapping instruction
  2d:	48 8b 98 b0 00 00 00 	mov    0xb0(%rax),%rbx
  34:	48 85 db             	test   %rbx,%rbx
  37:	0f 84 9a 00 00 00    	je     0xd7
  3d:	e8                   	.byte 0xe8
  3e:	27                   	(bad)
  3f:	3a                   	.byte 0x3a