[v5.15] general protection fault in sk_psock_verdict_data_ready

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7b232985052f Linux 5.15.199
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15d9f65a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=ef15f3d0940979357342
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/eb9b5a40817d/disk-7b232985.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/23aac02682eb/vmlinux-7b232985.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9530bb775138/bzImage-7b232985.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ef15f3...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000019: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000000c8-0x00000000000000cf]
CPU: 0 PID: 1115 Comm: syz.4.43057 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:sk_psock_verdict_data_ready+0x143/0x1d0 net/core/skmsg.c:1251
Code: 24 50 48 c7 44 24 48 01 00 00 00 43 80 3c 2e 00 74 08 4c 89 ff e8 ed 3c c2 f9 41 bc c8 00 00 00 4d 03 27 4c 89 e0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 e7 e8 ce 3c c2 f9 48 8b 7c 24 18 48 8d
RSP: 0018:ffffc9000310f800 EFLAGS: 00010202
RAX: 0000000000000019 RBX: 1ffff92000621f04 RCX: 0000000000080000
RDX: ffffc90003d33000 RSI: 0000000000064f91 RDI: 0000000000064f92
RBP: ffffc9000310f8d0 R08: ffffc9000310f85f R09: ffffc9000310f840
R10: dffffc0000000000 R11: fffff52000621f0c R12: 00000000000000c8
R13: dffffc0000000000 R14: 1ffff1101019bcc4 R15: ffff888080cde620
FS: 00007f8cccfad6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000004fc000 CR3: 0000000065c92000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<TASK>
unix_stream_sendmsg+0x7d1/0xc90 net/unix/af_unix.c:2110
sock_sendmsg_nosec net/socket.c:706 [inline]
__sock_sendmsg net/socket.c:718 [inline]
____sys_sendmsg+0x5b7/0x8f0 net/socket.c:2445
___sys_sendmsg+0x236/0x2e0 net/socket.c:2499
__sys_sendmsg net/socket.c:2528 [inline]
__do_sys_sendmsg net/socket.c:2537 [inline]
__se_sys_sendmsg+0x1af/0x290 net/socket.c:2535
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f8cced51f79
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:00007f8cccfad028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f8ccefccfa0 RCX: 00007f8cced51f79
RDX: 0000000000000003 RSI: 0000200000000980 RDI: 0000000000000006
RBP: 00007f8ccede86e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8ccefcd038 R14: 00007f8ccefccfa0 R15: 00007ffc3d966f78
</TASK>
Modules linked in:
---[ end trace c39d218c00820b46 ]---
RIP: 0010:sk_psock_verdict_data_ready+0x143/0x1d0 net/core/skmsg.c:1251
Code: 24 50 48 c7 44 24 48 01 00 00 00 43 80 3c 2e 00 74 08 4c 89 ff e8 ed 3c c2 f9 41 bc c8 00 00 00 4d 03 27 4c 89 e0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 e7 e8 ce 3c c2 f9 48 8b 7c 24 18 48 8d
RSP: 0018:ffffc9000310f800 EFLAGS: 00010202
RAX: 0000000000000019 RBX: 1ffff92000621f04 RCX: 0000000000080000
RDX: ffffc90003d33000 RSI: 0000000000064f91 RDI: 0000000000064f92
RBP: ffffc9000310f8d0 R08: ffffc9000310f85f R09: ffffc9000310f840
R10: dffffc0000000000 R11: fffff52000621f0c R12: 00000000000000c8
R13: dffffc0000000000 R14: 1ffff1101019bcc4 R15: ffff888080cde620
FS: 00007f8cccfad6c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555565a4c4e8 CR3: 0000000065c92000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000200000000300
DR3: 0000000000000000 DR6: 00000000ffff0ff1 DR7: 0000000000000600
----------------
Code disassembly (best guess):
0: 24 50 and $0x50,%al
2: 48 c7 44 24 48 01 00 movq $0x1,0x48(%rsp)
9: 00 00
b: 43 80 3c 2e 00 cmpb $0x0,(%r14,%r13,1)
10: 74 08 je 0x1a
12: 4c 89 ff mov %r15,%rdi
15: e8 ed 3c c2 f9 call 0xf9c23d07
1a: 41 bc c8 00 00 00 mov $0xc8,%r12d
20: 4d 03 27 add (%r15),%r12
23: 4c 89 e0 mov %r12,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 4c 89 e7 mov %r12,%rdi
34: e8 ce 3c c2 f9 call 0xf9c23d07
39: 48 8b 7c 24 18 mov 0x18(%rsp),%rdi
3e: 48 rex.W
3f: 8d .byte 0x8d


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