[moderation] [net?] general protection fault in find_match (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 53663f4103ff Merge tag 'nfs-for-6.5-2' of git://git.linux-..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=127d6d60680000
kernel config: https://syzkaller.appspot.com/x/.config?x=1e4a882f77ed77bd
dashboard link: https://syzkaller.appspot.com/bug?extid=8a252c706e77c40cc1a6
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386
CC: [b...@vger.kernel.org da...@davemloft.net dsa...@kernel.org edum...@google.com ku...@kernel.org linux-...@vger.kernel.org net...@vger.kernel.org pab...@redhat.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/20ba193a978f/disk-53663f41.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2b53a72efa77/vmlinux-53663f41.xz
kernel image: https://storage.googleapis.com/syzbot-assets/16cac9116c59/bzImage-53663f41.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8a252c...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc00000000c9: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000648-0x000000000000064f]
CPU: 1 PID: 8865 Comm: syz-executor.0 Not tainted 6.5.0-rc7-syzkaller-00013-g53663f4103ff #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
RIP: 0010:rt6_probe net/ipv6/route.c:652 [inline]
RIP: 0010:find_match+0x8b5/0xf40 net/ipv6/route.c:754
Code: b9 99 f8 48 8b 85 38 ff ff ff 48 c7 45 b0 00 00 00 00 48 8d b8 48 06 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 19 05 00 00 48 8b 85 38 ff ff
RSP: 0000:ffffc9000bbdeba0 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90003bc1000
RDX: 00000000000000c9 RSI: ffffffff88ec4f5e RDI: 0000000000000648
RBP: ffffc9000bbdec80 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: f024070cdc46132c R12: 000000000000000a
R13: 1ffff9200177bd7e R14: ffff888029d16a20 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9900000(0063) knlGS:00000000f7f4fb40
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000020438000 CR3: 000000002fb44000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
rt6_nh_find_match+0xfa/0x1a0 net/ipv6/route.c:780
nexthop_for_each_fib6_nh+0x262/0x490 net/ipv4/nexthop.c:1248
__find_rr_leaf+0x6e3/0xe00 net/ipv6/route.c:821
find_rr_leaf net/ipv6/route.c:849 [inline]
rt6_select net/ipv6/route.c:893 [inline]
fib6_table_lookup+0x57e/0xa30 net/ipv6/route.c:2181
ip6_pol_route+0x1c1/0x1220 net/ipv6/route.c:2217
pol_lookup_func include/net/ip6_fib.h:576 [inline]
__fib6_rule_action net/ipv6/fib6_rules.c:233 [inline]
fib6_rule_action+0x26e/0x830 net/ipv6/fib6_rules.c:267
fib_rules_lookup+0x360/0xc50 net/core/fib_rules.c:318
fib6_rule_lookup+0x3dd/0x5f0 net/ipv6/fib6_rules.c:108
ip6_route_output_flags_noref net/ipv6/route.c:2625 [inline]
ip6_route_output_flags+0x1d2/0x650 net/ipv6/route.c:2637
ip6_route_output include/net/ip6_route.h:94 [inline]
ip6_dst_lookup_tail.constprop.0+0x56e/0x15f0 net/ipv6/ip6_output.c:1111
ip6_dst_lookup_flow+0x99/0x1c0 net/ipv6/ip6_output.c:1241
sctp_v6_get_dst+0x6a9/0x1fd0 net/sctp/ipv6.c:327
sctp_transport_route+0x12c/0x350 net/sctp/transport.c:455
sctp_assoc_add_peer+0x73a/0x1530 net/sctp/associola.c:662
sctp_connect_new_asoc+0x204/0x780 net/sctp/socket.c:1098
sctp_sendmsg_new_asoc net/sctp/socket.c:1692 [inline]
sctp_sendmsg+0x15c2/0x1e80 net/sctp/socket.c:2003
inet_sendmsg+0x9d/0xe0 net/ipv4/af_inet.c:830
sock_sendmsg_nosec net/socket.c:725 [inline]
sock_sendmsg+0xd9/0x180 net/socket.c:748
____sys_sendmsg+0x6ac/0x940 net/socket.c:2494
___sys_sendmsg+0x135/0x1d0 net/socket.c:2548
__sys_sendmsg+0x117/0x1e0 net/socket.c:2577
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0x61/0xe0 arch/x86/entry/common.c:178
do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
entry_SYSENTER_compat_after_hwframe+0x70/0x82
RIP: 0023:0xf7f54579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f7f4f5ac EFLAGS: 00000292 ORIG_RAX: 0000000000000172
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000200000c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:rt6_probe net/ipv6/route.c:652 [inline]
RIP: 0010:find_match+0x8b5/0xf40 net/ipv6/route.c:754
Code: b9 99 f8 48 8b 85 38 ff ff ff 48 c7 45 b0 00 00 00 00 48 8d b8 48 06 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e 19 05 00 00 48 8b 85 38 ff ff
RSP: 0000:ffffc9000bbdeba0 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90003bc1000
RDX: 00000000000000c9 RSI: ffffffff88ec4f5e RDI: 0000000000000648
RBP: ffffc9000bbdec80 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: f024070cdc46132c R12: 000000000000000a
R13: 1ffff9200177bd7e R14: ffff888029d16a20 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9800000(0063) knlGS:00000000f7f4fb40
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f7354170 CR3: 000000002fb44000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
0: 99 cltd
1: f8 clc
2: 48 8b 85 38 ff ff ff mov -0xc8(%rbp),%rax
9: 48 c7 45 b0 00 00 00 movq $0x0,-0x50(%rbp)
10: 00
11: 48 8d b8 48 06 00 00 lea 0x648(%rax),%rdi
18: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
1f: fc ff df
22: 48 89 fa mov %rdi,%rdx
25: 48 c1 ea 03 shr $0x3,%rdx
* 29: 0f b6 04 02 movzbl (%rdx,%rax,1),%eax <-- trapping instruction
2d: 84 c0 test %al,%al
2f: 74 08 je 0x39
31: 3c 03 cmp $0x3,%al
33: 0f 8e 19 05 00 00 jle 0x552
39: 48 rex.W
3a: 8b .byte 0x8b
3b: 85 38 test %edi,(%rax)
3d: ff (bad)
3e: ff .byte 0xff


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.