[v6.1] BUG: unable to handle kernel paging request in find_match

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: da3c5173c55f Linux 6.1.140
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=110e6bf4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2bfe5a2f04bb30e3
dashboard link: https://syzkaller.appspot.com/bug?extid=123b13f747b4d5abf71f
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2c3ee4de68a1/disk-da3c5173.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/19742d73f52b/vmlinux-da3c5173.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0ffdd39d32ee/Image-da3c5173.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+123b13...@syzkaller.appspotmail.com

Unable to handle kernel paging request at virtual address dfff800000000068
KASAN: null-ptr-deref in range [0x0000000000000340-0x0000000000000347]
Mem abort info:
ESR = 0x0000000096000006
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x06: level 2 translation fault
Data abort info:
ISV = 0, ISS = 0x00000006
CM = 0, WnR = 0
[dfff800000000068] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 9475 Comm: syz.5.1134 Not tainted 6.1.140-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
pstate: 40400005 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __in6_dev_get include/net/addrconf.h:323 [inline]
pc : ip6_ignore_linkdown include/net/addrconf.h:414 [inline]
pc : find_match+0xa0/0xb0c net/ipv6/route.c:784
lr : find_match+0x74/0xb0c net/ipv6/route.c:781
sp : ffff8000080166c0
x29: ffff8000080166e0 x28: 1fffe000189b28c4 x27: dfff800000000000
x26: 0000000000000340 x25: ffff0000c4d94637 x24: 0000000000000201
x23: 0000000000000002 x22: ffff0000c4d94620 x21: 0000000000000000
x20: 1fffe000189b28c6 x19: 0000000000000000 x18: ffff800011a7bd00
x17: 0000000000000000 x16: ffff8000082d076c x15: 0000000000000000
x14: 000000000000c0fe x13: 1ffff00002a0e0b1 x12: 0000000000ff0100
x11: ff0080001077823c x10: 0000000000000000 x9 : ffff0000de881bc0
x8 : 0000000000000068 x7 : ffff800008016a70 x6 : 0000000000000002
x5 : ffff800008016a70 x4 : ffff800008016a60 x3 : 0000000000000002
x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
__in6_dev_get include/net/addrconf.h:323 [inline]
ip6_ignore_linkdown include/net/addrconf.h:414 [inline]
find_match+0xa0/0xb0c net/ipv6/route.c:784
rt6_nh_find_match+0xcc/0x138 net/ipv6/route.c:824
nexthop_for_each_fib6_nh+0x1a8/0x3d0 net/ipv4/nexthop.c:1243
__find_rr_leaf+0x3b8/0x5c8 net/ipv6/route.c:865
find_rr_leaf net/ipv6/route.c:893 [inline]
rt6_select net/ipv6/route.c:937 [inline]
fib6_table_lookup+0x308/0x8b8 net/ipv6/route.c:2223
ip6_pol_route+0x1f4/0x1024 net/ipv6/route.c:2259
ip6_pol_route_output+0x60/0x94 net/ipv6/route.c:2634
pol_lookup_func include/net/ip6_fib.h:579 [inline]
fib6_rule_lookup+0x258/0x4a8 net/ipv6/fib6_rules.c:121
ip6_route_output_flags_noref+0x250/0x314 net/ipv6/route.c:2666
ip6_route_output_flags+0xe4/0x368 net/ipv6/route.c:2679
ip6_route_output include/net/ip6_route.h:98 [inline]
ip6_dst_lookup_tail+0x168/0x12c0 net/ipv6/ip6_output.c:1124
ip6_dst_lookup_flow+0x54/0xe0 net/ipv6/ip6_output.c:1255
geneve_get_v6_dst+0x648/0x954 drivers/net/geneve.c:900
geneve6_xmit_skb drivers/net/geneve.c:1037 [inline]
geneve_xmit+0x970/0x2f18 drivers/net/geneve.c:1121
__netdev_start_xmit include/linux/netdevice.h:4896 [inline]
netdev_start_xmit include/linux/netdevice.h:4910 [inline]
xmit_one net/core/dev.c:3658 [inline]
dev_hard_start_xmit+0x244/0x8e0 net/core/dev.c:3674
__dev_queue_xmit+0x155c/0x309c net/core/dev.c:4334
dev_queue_xmit include/linux/netdevice.h:3051 [inline]
neigh_hh_output include/net/neighbour.h:528 [inline]
neigh_output include/net/neighbour.h:542 [inline]
ip6_finish_output2+0xd2c/0x1844 net/ipv6/ip6_output.c:138
__ip6_finish_output net/ipv6/ip6_output.c:205 [inline]
ip6_finish_output+0x594/0x930 net/ipv6/ip6_output.c:216
NF_HOOK_COND include/linux/netfilter.h:291 [inline]
ip6_output+0x274/0x500 net/ipv6/ip6_output.c:237
dst_output include/net/dst.h:453 [inline]
NF_HOOK include/linux/netfilter.h:302 [inline]
ndisc_send_skb+0xc38/0x1680 net/ipv6/ndisc.c:513
ndisc_send_rs+0x378/0x514 net/ipv6/ndisc.c:723
addrconf_rs_timer+0x2f4/0x574 net/ipv6/addrconf.c:3985
call_timer_fn+0x1b8/0x964 kernel/time/timer.c:1504
expire_timers kernel/time/timer.c:1549 [inline]
__run_timers+0x460/0x6bc kernel/time/timer.c:1820
run_timer_softirq+0x7c/0x114 kernel/time/timer.c:1833
handle_softirqs+0x318/0xc6c kernel/softirq.c:578
__do_softirq+0x14/0x20 kernel/softirq.c:612
____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:80
call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:893
do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:85
invoke_softirq kernel/softirq.c:459 [inline]
__irq_exit_rcu+0x23c/0x43c kernel/softirq.c:661
irq_exit_rcu+0x14/0x84 kernel/softirq.c:673
__el1_irq arch/arm64/kernel/entry-common.c:472 [inline]
el1_interrupt+0x38/0x54 arch/arm64/kernel/entry-common.c:486
el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:491
el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:581
arch_local_irq_restore arch/arm64/include/asm/irqflags.h:122 [inline]
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]
_raw_spin_unlock_irqrestore+0x58/0xac kernel/locking/spinlock.c:194
spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
__wake_up_common_lock kernel/sched/wait.c:140 [inline]
__wake_up_sync_key+0x11c/0x178 kernel/sched/wait.c:208
__unix_dgram_recvmsg+0x37c/0xb00 net/unix/af_unix.c:2454
unix_dgram_recvmsg+0xd0/0xe8 net/unix/af_unix.c:2524
sock_recvmsg_nosec net/socket.c:1022 [inline]
____sys_recvmsg+0x62c/0x71c net/socket.c:2736
___sys_recvmsg net/socket.c:2780 [inline]
do_recvmmsg+0x364/0x96c net/socket.c:2874
__sys_recvmmsg net/socket.c:2953 [inline]
__do_sys_recvmmsg net/socket.c:2976 [inline]
__se_sys_recvmmsg net/socket.c:2969 [inline]
__arm64_sys_recvmmsg+0x17c/0x238 net/socket.c:2969
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: 960576aa f94002c8 910d011a d343ff48 (387b6908)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 960576aa bl 0xfffffffff815daa8
4: f94002c8 ldr x8, [x22]
8: 910d011a add x26, x8, #0x340
c: d343ff48 lsr x8, x26, #3
* 10: 387b6908 ldrb w8, [x8, x27] <-- trapping instruction


---
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 syzk...@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

[syzbot]

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