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BUG: KASAN: global-out-of-bounds in fib6_ifup+0x257/0x2a0 net/ipv6/route.c:4815
Read of size 8 at addr ffffffff9af82c90 by task syz.2.2498/17447

CPU: 1 UID: 0 PID: 17447 Comm: syz.2.2498 Not tainted 6.15.0-rc6-syzkaller-00051-g405e6c37c89e #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+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xc3/0x670 mm/kasan/report.c:521
 kasan_report+0xe0/0x110 mm/kasan/report.c:634
 fib6_ifup+0x257/0x2a0 net/ipv6/route.c:4815
 fib6_clean_node+0x2a7/0x5b0 net/ipv6/ip6_fib.c:2199
 fib6_walk_continue+0x452/0x8d0 net/ipv6/ip6_fib.c:2124
 fib6_walk+0x182/0x370 net/ipv6/ip6_fib.c:2172
 fib6_clean_tree+0xd4/0x110 net/ipv6/ip6_fib.c:2252
 __fib6_clean_all+0x107/0x2d0 net/ipv6/ip6_fib.c:2268
 rt6_sync_up+0xc9/0x170 net/ipv6/route.c:4837
 addrconf_notify+0x1709/0x19e0 net/ipv6/addrconf.c:3732
 notifier_call_chain+0xbc/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2176
 netif_state_change+0x165/0x3b0 net/core/dev.c:1530
 netdev_state_change+0xaa/0x240 net/core/dev_api.c:365
 __tun_chr_ioctl+0x2522/0x4740 drivers/net/tun.c:3279
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl fs/ioctl.c:892 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f67ef38e969
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:00007f67f0260038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f67ef5b5fa0 RCX: 00007f67ef38e969
RDX: 0000000000000003 RSI: 00000000400454cc RDI: 04000000000000c8
RBP: 00007f67ef410ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f67ef5b5fa0 R15: 00007ffcc6452808
 </TASK>

The buggy address belongs to the variable:
 __key.0+0x30/0x40

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1af82
flags: 0xfff00000002000(reserved|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000002000 ffffea00006be088 ffffea00006be088 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner info is not present (never set?)

Memory state around the buggy address:
 ffffffff9af82b80: f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9
 ffffffff9af82c00: f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9 00 00 f9 f9
>ffffffff9af82c80: f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9 00 00 00 00
                         ^
 ffffffff9af82d00: 00 00 00 00 00 00 00 00 00 00 00 f9 f9 f9 f9 f9
 ffffffff9af82d80: 00 00 f9 f9 f9 f9 f9 f9 00 00 f9 f9 f9 f9 f9 f9
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