Re: [syzbot] [net?] kernel BUG in pn_socket_autobind

[syzbot <syzbot+b3c0e6a240078433c42b@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    6596a02b2078 Merge tag 'drm-next-2026-04-22' of https://gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15ca74ce580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3e19fa1907a3dfda
dashboard link: https://syzkaller.appspot.com/bug?extid=b3c0e6a240078433c42b
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17330cce580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=107ed1ba580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-6596a02b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1e78cc4623b5/vmlinux-6596a02b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7ae78b19bafa/bzImage-6596a02b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b3c0e6a240078433c42b@syzkaller.appspotmail.com

------------[ cut here ]------------
kernel BUG at net/phonet/socket.c:213!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 6116 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:pn_socket_autobind net/phonet/socket.c:213 [inline]
RIP: 0010:pn_socket_autobind+0x14c/0x170 net/phonet/socket.c:202
Code: 00 00 00 00 48 8b 44 24 58 65 48 2b 05 55 4d 47 09 75 2a 48 83 c4 60 89 d8 5b 5d 41 5c 41 5d e9 1a f8 d0 00 e8 15 78 3c f7 90 <0f> 0b e8 cd 30 aa f7 eb 9e e8 26 31 aa f7 e9 6c ff ff ff e8 7c b8
RSP: 0018:ffffc90003d5fa30 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8acd028a
RDX: ffff88802b48ca00 RSI: ffffffff8acd02cb RDI: ffff88802b48ca00
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff920007abf46
R13: dffffc0000000000 R14: 1ffff920007abf61 R15: ffffc90003d5fe48
FS:  00007f523dc816c0(0000) GS:ffff8880d62db000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdf9b231e9c CR3: 000000004a755000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 pn_socket_sendmsg+0x43/0xe0 net/phonet/socket.c:421
 sock_sendmsg_nosec net/socket.c:787 [inline]
 __sock_sendmsg net/socket.c:802 [inline]
 ____sys_sendmsg+0x9e1/0xb70 net/socket.c:2698
 ___sys_sendmsg+0x190/0x1e0 net/socket.c:2752
 __sys_sendmsg+0x170/0x220 net/socket.c:2784
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f523cd9c819
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:00007f523dc81028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f523d015fa0 RCX: 00007f523cd9c819
RDX: 0000000004044004 RSI: 0000200000000200 RDI: 000000000000000a
RBP: 00007f523ce32c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f523d016038 R14: 00007f523d015fa0 R15: 00007ffe40f56cd8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:pn_socket_autobind net/phonet/socket.c:213 [inline]
RIP: 0010:pn_socket_autobind+0x14c/0x170 net/phonet/socket.c:202
Code: 00 00 00 00 48 8b 44 24 58 65 48 2b 05 55 4d 47 09 75 2a 48 83 c4 60 89 d8 5b 5d 41 5c 41 5d e9 1a f8 d0 00 e8 15 78 3c f7 90 <0f> 0b e8 cd 30 aa f7 eb 9e e8 26 31 aa f7 e9 6c ff ff ff e8 7c b8
RSP: 0018:ffffc90003d5fa30 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8acd028a
RDX: ffff88802b48ca00 RSI: ffffffff8acd02cb RDI: ffff88802b48ca00
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff920007abf46
R13: dffffc0000000000 R14: 1ffff920007abf61 R15: ffffc90003d5fe48
FS:  00007f523dc816c0(0000) GS:ffff8880d62db000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdf9b231e9c CR3: 000000004a755000 CR4: 0000000000352ef0


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