==================================================================
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/1922

CPU: 2 UID: 0 PID: 1922 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]
 nsim_destroy+0x135/0x710 drivers/net/netdevsim/netdev.c:1021
 __nsim_dev_port_del+0x189/0x240 drivers/net/netdevsim/dev.c:1428
 nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1440 [inline]
 nsim_dev_reload_destroy+0x108/0x4d0 drivers/net/netdevsim/dev.c:1661
 nsim_drv_remove+0x52/0x1d0 drivers/net/netdevsim/dev.c:1676
 device_remove+0xc8/0x170 drivers/base/dd.c:567
 __device_release_driver drivers/base/dd.c:1273 [inline]
 device_release_driver_internal+0x44a/0x610 drivers/base/dd.c:1296
 bus_remove_device+0x22f/0x420 drivers/base/bus.c:579
 device_del+0x396/0x9f0 drivers/base/core.c:3855
 device_unregister+0x1d/0xc0 drivers/base/core.c:3896
 nsim_bus_dev_del drivers/net/netdevsim/bus.c:462 [inline]
 del_device_store+0x346/0x4b0 drivers/net/netdevsim/bus.c:226
 bus_attr_store+0x71/0xb0 drivers/base/bus.c:172
 sysfs_kf_write+0x117/0x170 fs/sysfs/file.c:139
 kernfs_fop_write_iter+0x33d/0x500 fs/kernfs/file.c:334
 new_sync_write fs/read_write.c:586 [inline]
 vfs_write+0x5ae/0x1150 fs/read_write.c:679
 ksys_write+0x12b/0x250 fs/read_write.c:731
 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: 0033:0x7fc22778bc1f
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:00007ffe72d0a3d0 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fc22778bc1f
RDX: 0000000000000001 RSI: 00007ffe72d0a420 RDI: 0000000000000005
RBP: 00007fc22780f4fd R08: 0000000000000000 R09: 00007ffe72d0a227
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 00007ffe72d0a420 R14: 00007fc2284d4620 R15: 0000000000000003
 </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
==================================================================