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BUG: KASAN: global-out-of-bounds in fib6_ifdown+0x7f5/0x8f0 net/ipv6/route.c:4863
Read of size 8 at addr ffffffff9ac27510 by task syz-executor/22492

CPU: 3 UID: 0 PID: 22492 Comm: syz-executor Not tainted 6.14.0-rc6-syzkaller-00016-g0fed89a961ea #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
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+0xd9/0x110 mm/kasan/report.c:634
 fib6_ifdown+0x7f5/0x8f0 net/ipv6/route.c:4863
 fib6_clean_node+0x2a5/0x5b0 net/ipv6/ip6_fib.c:2199
 fib6_walk_continue+0x44f/0x8d0 net/ipv6/ip6_fib.c:2124
 fib6_walk+0x182/0x370 net/ipv6/ip6_fib.c:2172
 fib6_clean_tree+0xd7/0x120 net/ipv6/ip6_fib.c:2252
 __fib6_clean_all+0x100/0x2d0 net/ipv6/ip6_fib.c:2268
 rt6_sync_down_dev net/ipv6/route.c:4913 [inline]
 rt6_disable_ip+0x2ef/0x940 net/ipv6/route.c:4918
 addrconf_ifdown.isra.0+0x126/0x1af0 net/ipv6/addrconf.c:3849
 addrconf_notify+0x220/0x19c0 net/ipv6/addrconf.c:3772
 notifier_call_chain+0xb7/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2206
 call_netdevice_notifiers_extack net/core/dev.c:2244 [inline]
 call_netdevice_notifiers net/core/dev.c:2258 [inline]
 dev_close_many+0x333/0x6a0 net/core/dev.c:1748
 unregister_netdevice_many_notify+0x48a/0x1f30 net/core/dev.c:11856
 unregister_netdevice_many net/core/dev.c:11948 [inline]
 unregister_netdevice_queue+0x307/0x3f0 net/core/dev.c:11818
 unregister_netdevice include/linux/netdevice.h:3337 [inline]
 __tun_detach+0x1241/0x1530 drivers/net/tun.c:685
 tun_detach drivers/net/tun.c:701 [inline]
 tun_chr_close+0xc2/0x230 drivers/net/tun.c:3517
 __fput+0x3ff/0xb70 fs/file_table.c:464
 task_work_run+0x14e/0x250 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0xad8/0x2d70 kernel/exit.c:938
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1087
 __do_sys_exit_group kernel/exit.c:1098 [inline]
 __se_sys_exit_group kernel/exit.c:1096 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1096
 x64_sys_call+0x151f/0x1720 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcf8e18d169
Code: Unable to access opcode bytes at 0x7fcf8e18d13f.
RSP: 002b:00007fff0d06e1b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fcf8e18d169
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000043
RBP: 00007fcf8e1ed8d0 R08: 00007fff0d06bf57 R09: 0000000000000003
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000003 R14: 00000000ffffffff R15: 00007fff0d06e370
 </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:0x1ac27
flags: 0xfff00000002000(reserved|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000002000 ffffea00006b09c8 ffffea00006b09c8 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:
 ffffffff9ac27400: f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9
 ffffffff9ac27480: f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9 00 00 f9 f9
>ffffffff9ac27500: f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9 00 00 00 00
                         ^
 ffffffff9ac27580: 00 00 00 00 00 00 00 00 00 00 00 f9 f9 f9 f9 f9
 ffffffff9ac27600: 00 00 f9 f9 f9 f9 f9 f9 00 00 f9 f9 f9 f9 f9 f9
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