------------[ cut here ]------------
UBSAN: array-index-out-of-bounds in ./include/net/ipv6.h:616:34
index 20 is out of range for type '__u8 [16]'
CPU: 1 UID: 0 PID: 19246 Comm: syz.5.2530 Not tainted 6.15.0-syzkaller-07774-g90b83efa6701 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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_out_of_bounds+0x11c/0x160 lib/ubsan.c:453
 ipv6_addr_prefix+0xf2/0x110 include/net/ipv6.h:616
 ip6_route_info_create+0x4b6/0x870 net/ipv6/route.c:3793
 ip6_route_add+0x26/0x1d0 net/ipv6/route.c:3889
 addrconf_prefix_route+0x2fd/0x510 net/ipv6/addrconf.c:2487
 addrconf_prefix_rcv+0x1808/0x1f70 net/ipv6/addrconf.c:2878
 ndisc_router_discovery+0x1c49/0x3550 net/ipv6/ndisc.c:1570
 ndisc_rcv+0x3fa/0x620 net/ipv6/ndisc.c:1874
 icmpv6_rcv+0x17c6/0x1c50 net/ipv6/icmp.c:988
 ip6_protocol_deliver_rcu+0xf89/0x1520 net/ipv6/ip6_input.c:436
 ip6_input_finish+0x102/0x180 net/ipv6/ip6_input.c:480
 NF_HOOK include/linux/netfilter.h:317 [inline]
 NF_HOOK include/linux/netfilter.h:311 [inline]
 ip6_input+0x105/0x2f0 net/ipv6/ip6_input.c:491
 ip6_mc_input+0x465/0xfd0 net/ipv6/ip6_input.c:588
 dst_input include/net/dst.h:469 [inline]
 dst_input include/net/dst.h:467 [inline]
 ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline]
 NF_HOOK include/linux/netfilter.h:317 [inline]
 NF_HOOK include/linux/netfilter.h:311 [inline]
 ipv6_rcv+0x45d/0x680 net/ipv6/ip6_input.c:309
 __netif_receive_skb_one_core+0x12d/0x1e0 net/core/dev.c:5977
 __netif_receive_skb+0x1d/0x160 net/core/dev.c:6090
 netif_receive_skb_internal net/core/dev.c:6176 [inline]
 netif_receive_skb+0x137/0x7b0 net/core/dev.c:6235
 tun_rx_batched.isra.0+0x3ee/0x740 drivers/net/tun.c:1509
 tun_get_user+0x28a2/0x3b80 drivers/net/tun.c:1938
 tun_chr_write_iter+0xdc/0x210 drivers/net/tun.c:1984
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x6c7/0x1150 fs/read_write.c:686
 ksys_write+0x12a/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f29c658d41f
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48
RSP: 002b:00007f29c74d4000 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f29c67b5fa0 RCX: 00007f29c658d41f
RDX: 00000000000003b6 RSI: 00002000000003c0 RDI: 00000000000000c8
RBP: 00007f29c6610ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000003b6 R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f29c67b5fa0 R15: 00007fffc7a3c3a8
 </TASK>
---[ end trace ]---