[syzbot] [net?] general protection fault in kernel_sock_shutdown (3)

[syzbot <syzbot+fae49d997eb56fa7c74d@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    d082ecbc71e9 Linux 6.14-rc4
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16f8ec98580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b1635bf4c5557b92
dashboard link: https://syzkaller.appspot.com/bug?extid=fae49d997eb56fa7c74d
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15d197a4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/323a5d590eec/disk-d082ecbc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f7c4b6e33fd9/vmlinux-d082ecbc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c518bbd55334/bzImage-d082ecbc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fae49d997eb56fa7c74d@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc000000000d: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f]
CPU: 0 UID: 0 PID: 6092 Comm: syz.0.24 Not tainted 6.14.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:kernel_sock_shutdown+0x47/0x70 net/socket.c:3660
Code: fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 33 48 b8 00 00 00 00 00 fc ff df 4c 8b 63 20 49 8d 7c 24 68 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 1a 49 8b 44 24 68 89 ee 48 89 df 5b 5d 41 5c ff e0
RSP: 0018:ffffc90002f27700 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888060d6f800 RCX: 0000000000000000
RDX: 000000000000000d RSI: ffffffff8925a602 RDI: 0000000000000068
RBP: 0000000000000002 R08: 0000000000000001 R09: fffffbfff2dd7dae
R10: ffffffff96ebed77 R11: 0000000000000001 R12: 0000000000000000
R13: ffff888024c5ae00 R14: ffff888024c59e40 R15: 0000000000000000
FS:  00007f57dba706c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000062018000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 udp_tunnel_sock_release+0x68/0x80 net/ipv4/udp_tunnel_core.c:181
 sctp_udp_sock_stop+0xf5/0x160 net/sctp/protocol.c:937
 proc_sctp_do_udp_port+0x261/0x450 net/sctp/sysctl.c:553
 proc_sys_call_handler+0x3c6/0x5a0 fs/proc/proc_sysctl.c:601
 iter_file_splice_write+0x90f/0x10b0 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x18f/0x6c0 fs/splice.c:1164
 splice_direct_to_actor+0x346/0xa40 fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0x178/0x250 fs/splice.c:1233
 do_sendfile+0xafb/0xe40 fs/read_write.c:1363
 __do_sys_sendfile64 fs/read_write.c:1424 [inline]
 __se_sys_sendfile64 fs/read_write.c:1410 [inline]
 __x64_sys_sendfile64+0x1da/0x220 fs/read_write.c:1410
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f57dab8d169
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:00007f57dba70038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f57dada6080 RCX: 00007f57dab8d169
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000003
RBP: 00007f57dac0e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000006 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f57dada6080 R15: 00007ffea4fcc208
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:kernel_sock_shutdown+0x47/0x70 net/socket.c:3660
Code: fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 33 48 b8 00 00 00 00 00 fc ff df 4c 8b 63 20 49 8d 7c 24 68 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 1a 49 8b 44 24 68 89 ee 48 89 df 5b 5d 41 5c ff e0
RSP: 0018:ffffc90002f27700 EFLAGS: 00010202

----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	df 48 89             	fisttps -0x77(%rax)
   3:	fa                   	cli
   4:	48 c1 ea 03          	shr    $0x3,%rdx
   8:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
   c:	75 33                	jne    0x41
   e:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  15:	fc ff df
  18:	4c 8b 63 20          	mov    0x20(%rbx),%r12
  1c:	49 8d 7c 24 68       	lea    0x68(%r12),%rdi
  21:	48 89 fa             	mov    %rdi,%rdx
  24:	48 c1 ea 03          	shr    $0x3,%rdx
* 28:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2c:	75 1a                	jne    0x48
  2e:	49 8b 44 24 68       	mov    0x68(%r12),%rax
  33:	89 ee                	mov    %ebp,%esi
  35:	48 89 df             	mov    %rbx,%rdi
  38:	5b                   	pop    %rbx
  39:	5d                   	pop    %rbp
  3a:	41 5c                	pop    %r12
  3c:	ff e0                	jmp    *%rax


---
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