[syzbot] [mptcp?] WARNING in mptcp_pm_alloc_anno_list

[syzbot <syzbot+c6fca020ebd279c7412a@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    8b98f34ce1d8 net: ipv6: Fix spelling mistake
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17d2b770580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=efe4e8ed5014b310
dashboard link: https://syzkaller.appspot.com/bug?extid=c6fca020ebd279c7412a
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ad0c8f9a1a48/disk-8b98f34c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3a8aacec88f6/vmlinux-8b98f34c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0a86c0c1690c/bzImage-8b98f34c.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c6fca020ebd279c7412a@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 7141 at net/mptcp/pm.c:353 mptcp_pm_alloc_anno_list+0x329/0x390 net/mptcp/pm.c:353
Modules linked in:
CPU: 0 UID: 0 PID: 7141 Comm: syz.3.339 Not tainted 6.16.0-rc3-syzkaller-00985-g8b98f34ce1d8 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:mptcp_pm_alloc_anno_list+0x329/0x390 net/mptcp/pm.c:353
Code: b0 01 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d e9 8c 26 15 00 cc e8 56 b2 6a f6 90 0f 0b 90 e9 8b fd ff ff e8 48 b2 6a f6 90 <0f> 0b 90 31 c0 eb d1 48 c7 c1 30 69 a1 8f 80 e1 07 80 c1 03 38 c1
RSP: 0018:ffffc9000b5a6db8 EFLAGS: 00010287
RAX: ffffffff8b559c28 RBX: ffff88807a3f9700 RCX: 0000000000080000
RDX: ffffc9000cbdd000 RSI: 000000000000318f RDI: 0000000000003190
RBP: 0000000000000000 R08: 00000000000a0002 R09: 0000000000000000
R10: 0000000000000000 R11: aa1414acffff0000 R12: ffff88814632f000
R13: ffff88807d852040 R14: dffffc0000000000 R15: ffff88807a3fa181
FS:  00007fb6c8df66c0(0000) GS:ffff888125c48000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb6c8df4fb8 CR3: 00000000339a2000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 mptcp_pm_create_subflow_or_signal_addr+0x1448/0x1c30 net/mptcp/pm_kernel.c:318
 mptcp_nl_add_subflow_or_signal_addr net/mptcp/pm_kernel.c:760 [inline]
 mptcp_pm_nl_add_addr_doit+0xe66/0x1460 net/mptcp/pm_kernel.c:840
 genl_family_rcv_msg_doit+0x215/0x300 net/netlink/genetlink.c:1115
 genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
 genl_rcv_msg+0x60e/0x790 net/netlink/genetlink.c:1210
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:729
 ____sys_sendmsg+0x505/0x830 net/socket.c:2614
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668
 __sys_sendmsg net/socket.c:2700 [inline]
 __do_sys_sendmsg net/socket.c:2705 [inline]
 __se_sys_sendmsg net/socket.c:2703 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2703
 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: 0033:0x7fb6caf8e929
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:00007fb6c8df6038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fb6cb1b5fa0 RCX: 00007fb6caf8e929
RDX: 0000000002000000 RSI: 0000200000000400 RDI: 000000000000000d
RBP: 00007fb6cb010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb6cb1b5fa0 R15: 00007ffe35e566e8
 </TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup