Re: [syzbot] [mm?] general protection fault in find_lock_task_mm

[syzbot <syzbot+c2e074db555379260750@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
UBSAN: shift-out-of-bounds in ip_finish_output2

------------[ cut here ]------------
UBSAN: shift-out-of-bounds in ./include/net/neighbour.h:306:44
shift exponent 32 is too large for 32-bit type 'unsigned int'
CPU: 0 UID: 0 PID: 12 Comm: kworker/u8:1 Not tainted 6.13.0-rc3-syzkaller-gf44d154d6e3d-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024
Workqueue: wg-kex-wg0 wg_packet_handshake_send_worker
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:120
 ubsan_epilogue lib/ubsan.c:231 [inline]
 __ubsan_handle_shift_out_of_bounds+0x2a5/0x480 lib/ubsan.c:468
 ___neigh_lookup_noref include/net/neighbour.h:306 [inline]
 __ipv4_neigh_lookup_noref include/net/arp.h:27 [inline]
 ip_neigh_gw4 include/net/route.h:383 [inline]
 ip_neigh_for_gw include/net/route.h:403 [inline]
 ip_finish_output2.cold+0x56/0x5b net/ipv4/ip_output.c:230
 __ip_finish_output net/ipv4/ip_output.c:314 [inline]
 __ip_finish_output+0x49e/0x950 net/ipv4/ip_output.c:296
 ip_finish_output+0x35/0x380 net/ipv4/ip_output.c:324
 NF_HOOK_COND include/linux/netfilter.h:303 [inline]
 ip_output+0x13b/0x2a0 net/ipv4/ip_output.c:434
 dst_output include/net/dst.h:450 [inline]
 ip_local_out+0x33e/0x4a0 net/ipv4/ip_output.c:130
 iptunnel_xmit+0x5d9/0xa00 net/ipv4/ip_tunnel_core.c:82
 send4+0x48e/0xe30 drivers/net/wireguard/socket.c:85
 wg_socket_send_skb_to_peer+0x196/0x220 drivers/net/wireguard/socket.c:175
 wg_socket_send_buffer_to_peer+0x148/0x1a0 drivers/net/wireguard/socket.c:200
 wg_packet_send_handshake_initiation+0x227/0x360 drivers/net/wireguard/send.c:40
 wg_packet_handshake_send_worker+0x1c/0x30 drivers/net/wireguard/send.c:51
 process_one_work+0x958/0x1b30 kernel/workqueue.c:3229
 process_scheduled_works kernel/workqueue.c:3310 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
---[ end trace ]---


Tested on:

commit:         f44d154d Merge tag 'soc-fixes-6.13' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12c9560f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c22efbd20f8da769
dashboard link: https://syzkaller.appspot.com/bug?extid=c2e074db555379260750
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=175f27e8580000