Message-ID: <692cfe39.a70a0220.2ea503.00ac.GAE@google.com>
Date: Sun, 30 Nov 2025 18:32:25 -0800
From: syzbot <syzbot+9b35e9bc0951140d13e6@...kaller.appspotmail.com>
To: davem@...emloft.net, dsahern@...nel.org, edumazet@...gle.com, 
	horms@...nel.org, kuba@...nel.org, linux-kernel@...r.kernel.org, 
	netdev@...r.kernel.org, pabeni@...hat.com, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [net?] kernel BUG in ip6_pol_route (2)

syzbot has found a reproducer for the following issue on:

HEAD commit:    e69c7c175115 Merge tag 'timers_urgent_for_v6.18_rc8' of gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14fe98c2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=38a0c4cddc846161
dashboard link: https://syzkaller.appspot.com/bug?extid=9b35e9bc0951140d13e6
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13ab4192580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12fe98c2580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1ba30df3c7a5/disk-e69c7c17.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/794674f290bd/vmlinux-e69c7c17.xz
kernel image: https://storage.googleapis.com/syzbot-assets/872c0363d566/bzImage-e69c7c17.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9b35e9bc0951140d13e6@...kaller.appspotmail.com

------------[ cut here ]------------
kernel BUG at net/ipv6/route.c:1473!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 6073 Comm: syz.2.34 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:rt6_make_pcpu_route net/ipv6/route.c:1473 [inline]
RIP: 0010:ip6_pol_route+0x117d/0x1180 net/ipv6/route.c:2305
Code: aa f8 e9 f4 fa ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 03 fb ff ff 48 89 df e8 9e cf aa f8 e9 f6 fa ff ff e8 64 0d 49 f8 90 <0f> 0b 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e
RSP: 0018:ffffc9000407f5a0 EFLAGS: 00010293
RAX: ffffffff89759fdc RBX: ffff888126ef4000 RCX: ffff88802ea13c00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000407f6b0 R08: ffffe8ffffd488af R09: 1ffffd1ffffa9115
R10: dffffc0000000000 R11: fffff91ffffa9116 R12: ffff888031da18c0
R13: ffffffff89758fc2 R14: dffffc0000000000 R15: 0000607ed8e548a8
FS:  0000555563d45500(0000) GS:ffff888126ef4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8a8bbe1760 CR3: 0000000031586000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 pol_lookup_func include/net/ip6_fib.h:617 [inline]
 fib6_rule_lookup+0x1fc/0x6f0 net/ipv6/fib6_rules.c:120
 ip6_route_output_flags_noref net/ipv6/route.c:2684 [inline]
 ip6_route_output_flags+0x364/0x5d0 net/ipv6/route.c:2696
 ip6_route_output include/net/ip6_route.h:93 [inline]
 ip6_dst_lookup_tail+0x1ae/0x1510 net/ipv6/ip6_output.c:1141
 ip6_dst_lookup_flow+0x47/0xe0 net/ipv6/ip6_output.c:1272
 tcp_v6_connect+0xbdb/0x18a0 net/ipv6/tcp_ipv6.c:281
 __inet_stream_connect+0x2ae/0xe70 net/ipv4/af_inet.c:679
 inet_stream_connect+0x66/0xa0 net/ipv4/af_inet.c:750
 __sys_connect_file net/socket.c:2102 [inline]
 __sys_connect+0x323/0x450 net/socket.c:2121
 __do_sys_connect net/socket.c:2127 [inline]
 __se_sys_connect net/socket.c:2124 [inline]
 __x64_sys_connect+0x7a/0x90 net/socket.c:2124
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7b578bf749
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:00007ffeb60b5268 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f7b57b15fa0 RCX: 00007f7b578bf749
RDX: 000000000000001c RSI: 0000200000000200 RDI: 0000000000000003
RBP: 00007f7b57943f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7b57b15fa0 R14: 00007f7b57b15fa0 R15: 0000000000000003
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:rt6_make_pcpu_route net/ipv6/route.c:1473 [inline]
RIP: 0010:ip6_pol_route+0x117d/0x1180 net/ipv6/route.c:2305
Code: aa f8 e9 f4 fa ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 03 fb ff ff 48 89 df e8 9e cf aa f8 e9 f6 fa ff ff e8 64 0d 49 f8 90 <0f> 0b 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e
RSP: 0018:ffffc9000407f5a0 EFLAGS: 00010293
RAX: ffffffff89759fdc RBX: ffff888126ef4000 RCX: ffff88802ea13c00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000407f6b0 R08: ffffe8ffffd488af R09: 1ffffd1ffffa9115
R10: dffffc0000000000 R11: fffff91ffffa9116 R12: ffff888031da18c0
R13: ffffffff89758fc2 R14: dffffc0000000000 R15: 0000607ed8e548a8
FS:  0000555563d45500(0000) GS:ffff888126ef4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f53a449f358 CR3: 0000000031586000 CR4: 00000000003526f0


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

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