[v5.15] kernel BUG in pn_socket_sendmsg

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 241d66fa280c Linux 5.15.208
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=120c2ac8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=594221e25bfda1656bb1
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/d3e9d10633a1/disk-241d66fa.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/beca1f713e4b/vmlinux-241d66fa.xz
kernel image: https://storage.googleapis.com/syzbot-assets/26a15a6e1c14/bzImage-241d66fa.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+594221...@syzkaller.appspotmail.com

netlink: 'syz.4.1265': attribute type 2 has an invalid length.
------------[ cut here ]------------
kernel BUG at net/phonet/socket.c:213!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 8532 Comm: syz.4.1265 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:pn_socket_autobind net/phonet/socket.c:213 [inline]
RIP: 0010:pn_socket_sendmsg+0x223/0x230 net/phonet/socket.c:422
Code: 41 5f 5d c3 e8 3e ff b0 00 89 d9 80 e1 07 fe c1 38 c1 0f 8c 0f ff ff ff 48 89 df e8 47 7a b2 f8 e9 02 ff ff ff e8 8d 5b 6d f8 <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 55 48 89 e5 41 57 41 56 41
RSP: 0018:ffffc9000418f9c0 EFLAGS: 00010287
RAX: ffffffff890bda83 RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc9000df09000 RSI: 0000000000000080 RDI: 0000000000000081
RBP: ffffc9000418fa70 R08: ffff88801ff7934b R09: 1ffff11003fef269
R10: dffffc0000000000 R11: ffffed1003fef26a R12: dffffc0000000000
R13: ffff888061e04200 R14: ffff88801ff792c0 R15: 1ffff92000831f3c
FS: 00007fe35aa4b6c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f960956fa08 CR3: 0000000079409000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
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: 0033:0x7fe35c7f1e59
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:00007fe35aa4b028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fe35ca6afa0 RCX: 00007fe35c7f1e59
RDX: 0000000004004081 RSI: 00002000000002c0 RDI: 0000000000000007
RBP: 00007fe35c887d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe35ca6b038 R14: 00007fe35ca6afa0 R15: 00007fff5b4f7108
</TASK>
Modules linked in:
---[ end trace 2c0e9a2c206cb1c2 ]---
RIP: 0010:pn_socket_autobind net/phonet/socket.c:213 [inline]
RIP: 0010:pn_socket_sendmsg+0x223/0x230 net/phonet/socket.c:422
Code: 41 5f 5d c3 e8 3e ff b0 00 89 d9 80 e1 07 fe c1 38 c1 0f 8c 0f ff ff ff 48 89 df e8 47 7a b2 f8 e9 02 ff ff ff e8 8d 5b 6d f8 <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 55 48 89 e5 41 57 41 56 41
RSP: 0018:ffffc9000418f9c0 EFLAGS: 00010287
RAX: ffffffff890bda83 RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc9000df09000 RSI: 0000000000000080 RDI: 0000000000000081
RBP: ffffc9000418fa70 R08: ffff88801ff7934b R09: 1ffff11003fef269
R10: dffffc0000000000 R11: ffffed1003fef26a R12: dffffc0000000000
R13: ffff888061e04200 R14: ffff88801ff792c0 R15: 1ffff92000831f3c
FS: 00007fe35aa4b6c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2d4c2d CR3: 0000000079409000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0a40c6fbd105 Linux 6.6.141
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16e26d96580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c5b35c4db8465904
dashboard link: https://syzkaller.appspot.com/bug?extid=8f8816d1a6eb0c8ceb3e

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/bef5f7e53495/disk-0a40c6fb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/61ce39aaab25/vmlinux-0a40c6fb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/43d2363e7871/bzImage-0a40c6fb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by: syzbot+8f8816...@syzkaller.appspotmail.com

EXT4-fs (loop2): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
netlink: 'syz.2.99': attribute type 2 has an invalid length.

------------[ cut here ]------------
kernel BUG at net/phonet/socket.c:213!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN

CPU: 1 PID: 6163 Comm: syz.2.99 Not tainted syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:pn_socket_autobind net/phonet/socket.c:213 [inline]

RIP: 0010:pn_socket_sendmsg+0x235/0x240 net/phonet/socket.c:422
Code: 41 5f 5d c3 e8 bc 6a cb 00 89 d9 80 e1 07 fe c1 38 c1 0f 8c 0f ff ff ff 48 89 df e8 25 8b 23 f8 e9 02 ff ff ff e8 0b 4c cb f7 <0f> 0b 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 55 48 89 e5 41 57 41
RSP: 0018:ffffc90005527960 EFLAGS: 00010283
RAX: ffffffff89bbdfe5 RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc9000d3a3000 RSI: 0000000000000050 RDI: 0000000000000051
RBP: ffffc90005527a10 R08: ffffffff8e8b3aef R09: 1ffffffff1d1675d
R10: dffffc0000000000 R11: fffffbfff1d1675e R12: dffffc0000000000
R13: ffff88805b44d400 R14: ffff8880300c0c80 R15: 1ffff92000aa4f30
FS: 00007f52907df6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 000055557be199f8 CR3: 000000002f0b8000 CR4: 00000000003506e0
Call Trace:
<TASK>
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
____sys_sendmsg+0x5ba/0x960 net/socket.c:2594
___sys_sendmsg+0x2a6/0x360 net/socket.c:2648
__sys_sendmsg net/socket.c:2677 [inline]
__do_sys_sendmsg net/socket.c:2686 [inline]
__se_sys_sendmsg+0x1c2/0x2b0 net/socket.c:2684
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f528f99ce59

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:00007f52907df028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f528fc15fa0 RCX: 00007f528f99ce59
RDX: 0000000004004081 RSI: 00002000000002c0 RDI: 0000000000000008
RBP: 00007f528fa32d6f R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 00007f528fc16038 R14: 00007f528fc15fa0 R15: 00007ffcc9eabff8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---

RIP: 0010:pn_socket_autobind net/phonet/socket.c:213 [inline]

RIP: 0010:pn_socket_sendmsg+0x235/0x240 net/phonet/socket.c:422
Code: 41 5f 5d c3 e8 bc 6a cb 00 89 d9 80 e1 07 fe c1 38 c1 0f 8c 0f ff ff ff 48 89 df e8 25 8b 23 f8 e9 02 ff ff ff e8 0b 4c cb f7 <0f> 0b 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 55 48 89 e5 41 57 41
RSP: 0018:ffffc90005527960 EFLAGS: 00010283
RAX: ffffffff89bbdfe5 RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc9000d3a3000 RSI: 0000000000000050 RDI: 0000000000000051
RBP: ffffc90005527a10 R08: ffffffff8e8b3aef R09: 1ffffffff1d1675d
R10: dffffc0000000000 R11: fffffbfff1d1675e R12: dffffc0000000000
R13: ffff88805b44d400 R14: ffff8880300c0c80 R15: 1ffff92000aa4f30
FS: 00007f52907df6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007f85b77d4ff8 CR3: 000000002f0b8000 CR4: 00000000003506e0

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 0a40c6fbd105 Linux 6.6.141
git tree: linux-6.6.y

console output: https://syzkaller.appspot.com/x/log.txt?x=10be542e580000

kernel config: https://syzkaller.appspot.com/x/.config?x=c5b35c4db8465904
dashboard link: https://syzkaller.appspot.com/bug?extid=8f8816d1a6eb0c8ceb3e
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17ca6d96580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=144eed6a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/bef5f7e53495/disk-0a40c6fb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/61ce39aaab25/vmlinux-0a40c6fb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/43d2363e7871/bzImage-0a40c6fb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8f8816...@syzkaller.appspotmail.com

netlink: 'syz.0.17': attribute type 2 has an invalid length.

------------[ cut here ]------------
kernel BUG at net/phonet/socket.c:213!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN

CPU: 1 PID: 5934 Comm: syz.0.17 Not tainted syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:pn_socket_autobind net/phonet/socket.c:213 [inline]
RIP: 0010:pn_socket_sendmsg+0x235/0x240 net/phonet/socket.c:422
Code: 41 5f 5d c3 e8 bc 6a cb 00 89 d9 80 e1 07 fe c1 38 c1 0f 8c 0f ff ff ff 48 89 df e8 25 8b 23 f8 e9 02 ff ff ff e8 0b 4c cb f7 <0f> 0b 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 55 48 89 e5 41 57 41

RSP: 0018:ffffc90003397960 EFLAGS: 00010293
RAX: ffffffff89bbdfe5 RBX: 0000000000000000 RCX: ffff88802c875a00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003397a10 R08: ffffffff8e8b3aef R09: 1ffffffff1d1675d

R10: dffffc0000000000 R11: fffffbfff1d1675e R12: dffffc0000000000

R13: ffff88805dcce000 R14: ffff88807abb0c80 R15: 1ffff92000672f30
FS: 00007fb751ba06c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007fb751b7eff8 CR3: 00000000739d3000 CR4: 00000000003506e0

Call Trace:
<TASK>
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
____sys_sendmsg+0x5ba/0x960 net/socket.c:2594
___sys_sendmsg+0x2a6/0x360 net/socket.c:2648
__sys_sendmsg net/socket.c:2677 [inline]
__do_sys_sendmsg net/socket.c:2686 [inline]
__se_sys_sendmsg+0x1c2/0x2b0 net/socket.c:2684
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2

RIP: 0033:0x7fb750d9ce59

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:00007fb751ba0028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb751015fa0 RCX: 00007fb750d9ce59
RDX: 0000000004004081 RSI: 00002000000002c0 RDI: 0000000000000006
RBP: 00007fb750e32d6f R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 00007fb751016038 R14: 00007fb751015fa0 R15: 00007ffeb68fa408

</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:pn_socket_autobind net/phonet/socket.c:213 [inline]
RIP: 0010:pn_socket_sendmsg+0x235/0x240 net/phonet/socket.c:422
Code: 41 5f 5d c3 e8 bc 6a cb 00 89 d9 80 e1 07 fe c1 38 c1 0f 8c 0f ff ff ff 48 89 df e8 25 8b 23 f8 e9 02 ff ff ff e8 0b 4c cb f7 <0f> 0b 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 55 48 89 e5 41 57 41

RSP: 0018:ffffc90003397960 EFLAGS: 00010293
RAX: ffffffff89bbdfe5 RBX: 0000000000000000 RCX: ffff88802c875a00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003397a10 R08: ffffffff8e8b3aef R09: 1ffffffff1d1675d

R10: dffffc0000000000 R11: fffffbfff1d1675e R12: dffffc0000000000

R13: ffff88805dcce000 R14: ffff88807abb0c80 R15: 1ffff92000672f30
FS: 00007fb751ba06c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007fb750dea540 CR3: 00000000739d3000 CR4: 00000000003506f0


---
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