Oops: general protection fault, probably for non-canonical address 0xdffffc00000000ac: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000560-0x0000000000000567]
CPU: 0 UID: 0 PID: 10831 Comm: syz.3.1251 Not tainted 6.16.0-rc5-syzkaller-00205-g531d0d32de3e #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:atmtcp_recv_control drivers/atm/atmtcp.c:93 [inline]
RIP: 0010:atmtcp_c_send+0x1da/0x950 drivers/atm/atmtcp.c:297
Code: 4d 8d 75 1a 4c 89 f0 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 15 06 00 00 41 0f b7 1e 4d 8d b7 60 05 00 00 4c 89 f0 48 c1 e8 03 <42> 0f b6 04 20 84 c0 0f 85 13 06 00 00 66 41 89 1e 4d 8d 75 1c 4c
RSP: 0018:ffffc9000d537950 EFLAGS: 00010206
RAX: 00000000000000ac RBX: 0000000000000000 RCX: 0000000000000002
RDX: ffff88801e77da00 RSI: 00000000ffffffff RDI: ffff88807b6770cc
RBP: ffff88807ca5adc0 R08: ffff88807b6770cb R09: 0000000000000002
R10: ffff88807b6770ca R11: ffffffff870eaa60 R12: dffffc0000000000
R13: ffff88807b6770c0 R14: 0000000000000560 R15: 0000000000000000
FS:  00007fb8d02056c0(0000) GS:ffff888125c1b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb8d0204f98 CR3: 0000000055d50000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 vcc_sendmsg+0xa13/0xc60 net/atm/common.c:645
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 sock_write_iter+0x258/0x330 net/socket.c:1131
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x54b/0xa90 fs/read_write.c:686
 ksys_write+0x145/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb8cf38e929
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:00007fb8d0205038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fb8cf5b6160 RCX: 00007fb8cf38e929
RDX: 000000000000000a RSI: 0000200000000000 RDI: 0000000000000004
RBP: 00007fb8cf410ca1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007fb8cf5b6160 R15: 00007ffdbd2c7278
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:atmtcp_recv_control drivers/atm/atmtcp.c:93 [inline]
RIP: 0010:atmtcp_c_send+0x1da/0x950 drivers/atm/atmtcp.c:297
Code: 4d 8d 75 1a 4c 89 f0 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 15 06 00 00 41 0f b7 1e 4d 8d b7 60 05 00 00 4c 89 f0 48 c1 e8 03 <42> 0f b6 04 20 84 c0 0f 85 13 06 00 00 66 41 89 1e 4d 8d 75 1c 4c
RSP: 0018:ffffc9000d537950 EFLAGS: 00010206
RAX: 00000000000000ac RBX: 0000000000000000 RCX: 0000000000000002
RDX: ffff88801e77da00 RSI: 00000000ffffffff RDI: ffff88807b6770cc
RBP: ffff88807ca5adc0 R08: ffff88807b6770cb R09: 0000000000000002
R10: ffff88807b6770ca R11: ffffffff870eaa60 R12: dffffc0000000000
R13: ffff88807b6770c0 R14: 0000000000000560 R15: 0000000000000000
FS:  00007fb8d02056c0(0000) GS:ffff888125c1b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb8d0204f98 CR3: 0000000055d50000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	4d 8d 75 1a          	lea    0x1a(%r13),%r14
   4:	4c 89 f0             	mov    %r14,%rax
   7:	48 c1 e8 03          	shr    $0x3,%rax
   b:	42 0f b6 04 20       	movzbl (%rax,%r12,1),%eax
  10:	84 c0                	test   %al,%al
  12:	0f 85 15 06 00 00    	jne    0x62d
  18:	41 0f b7 1e          	movzwl (%r14),%ebx
  1c:	4d 8d b7 60 05 00 00 	lea    0x560(%r15),%r14
  23:	4c 89 f0             	mov    %r14,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 0f b6 04 20       	movzbl (%rax,%r12,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	0f 85 13 06 00 00    	jne    0x64a
  37:	66 41 89 1e          	mov    %bx,(%r14)
  3b:	4d 8d 75 1c          	lea    0x1c(%r13),%r14
  3f:	4c                   	rex.WR