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BUG: KASAN: slab-out-of-bounds in fib6_drop_pcpu_from net/ipv6/ip6_fib.c:925 [inline]
BUG: KASAN: slab-out-of-bounds in fib6_purge_rt+0x1b3/0x5e0 net/ipv6/ip6_fib.c:937
Write of size 8 at addr ffff8880a65a16c4 by task kworker/u4:4/31438

CPU: 0 PID: 31438 Comm: kworker/u4:4 Not tainted 5.2.0-rc1+ #31
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:188
 __kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 kasan_report+0x12/0x20 mm/kasan/common.c:614
 check_memory_region_inline mm/kasan/generic.c:185 [inline]
 check_memory_region+0x123/0x190 mm/kasan/generic.c:191
 kasan_check_write+0x14/0x20 mm/kasan/common.c:100
 fib6_drop_pcpu_from net/ipv6/ip6_fib.c:925 [inline]
 fib6_purge_rt+0x1b3/0x5e0 net/ipv6/ip6_fib.c:937
 fib6_del_route net/ipv6/ip6_fib.c:1812 [inline]
 fib6_del+0xac2/0x10a0 net/ipv6/ip6_fib.c:1843
 fib6_clean_node+0x3a5/0x590 net/ipv6/ip6_fib.c:2005
 fib6_walk_continue+0x4a9/0x8e0 net/ipv6/ip6_fib.c:1927
 fib6_walk+0x9d/0x100 net/ipv6/ip6_fib.c:1975
 fib6_clean_tree+0xe0/0x120 net/ipv6/ip6_fib.c:2054
 __fib6_clean_all+0x118/0x2a0 net/ipv6/ip6_fib.c:2070
 fib6_clean_all+0x2b/0x40 net/ipv6/ip6_fib.c:2081
 rt6_sync_down_dev+0x134/0x150 net/ipv6/route.c:4169
 rt6_disable_ip+0x27/0x5f0 net/ipv6/route.c:4174
 addrconf_ifdown+0xa2/0x1220 net/ipv6/addrconf.c:3709
 addrconf_notify+0x5db/0x2270 net/ipv6/addrconf.c:3634
 notifier_call_chain+0xc2/0x230 kernel/notifier.c:95
 __raw_notifier_call_chain kernel/notifier.c:396 [inline]
 raw_notifier_call_chain+0x2e/0x40 kernel/notifier.c:403
 call_netdevice_notifiers_info+0x3f/0x90 net/core/dev.c:1753
 call_netdevice_notifiers_extack net/core/dev.c:1765 [inline]
 call_netdevice_notifiers net/core/dev.c:1779 [inline]
 dev_close_many+0x33f/0x6f0 net/core/dev.c:1522
 rollback_registered_many+0x43b/0xfc0 net/core/dev.c:8193
 unregister_netdevice_many.part.0+0x1b/0x1f0 net/core/dev.c:9324
 unregister_netdevice_many net/core/dev.c:9323 [inline]
 default_device_exit_batch+0x34e/0x410 net/core/dev.c:9793
 ops_exit_list.isra.0+0xfc/0x150 net/core/net_namespace.c:157
 cleanup_net+0x3fb/0x960 net/core/net_namespace.c:553
 process_one_work+0x989/0x1790 kernel/workqueue.c:2269
 worker_thread+0x98/0xe40 kernel/workqueue.c:2415
 kthread+0x354/0x420 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 8645:
 save_stack+0x23/0x90 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_kmalloc mm/kasan/common.c:489 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:462
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:503
 kmem_cache_alloc_trace+0x151/0x750 mm/slab.c:3555
 kmalloc include/linux/slab.h:547 [inline]
 kzalloc include/linux/slab.h:742 [inline]
 alloc_super+0x55/0x890 fs/super.c:202
 sget_fc+0x2af/0x940 fs/super.c:530
 kernfs_get_tree+0x197/0x980 fs/kernfs/mount.c:309
 cgroup_do_get_tree+0x112/0x4d0 kernel/cgroup/cgroup.c:2084
 cgroup1_get_tree+0xe0d/0x14f5 kernel/cgroup/cgroup-v1.c:1238
 vfs_get_tree+0x8e/0x390 fs/super.c:1476
 do_new_mount fs/namespace.c:2790 [inline]
 do_mount+0x138c/0x1c00 fs/namespace.c:3110
 ksys_mount+0xdb/0x150 fs/namespace.c:3319
 __do_sys_mount fs/namespace.c:3333 [inline]
 __se_sys_mount fs/namespace.c:3330 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3330
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8880a65a0c80
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 2628 bytes inside of
 4096-byte region [ffff8880a65a0c80, ffff8880a65a1c80)
The buggy address belongs to the page:
page:ffffea0002996800 refcount:1 mapcount:0 mapping:ffff8880aa400dc0 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea000214ff08 ffffea0001c67988 ffff8880aa400dc0
raw: 0000000000000000 ffff8880a65a0c80 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a65a1580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880a65a1600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880a65a1680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                           ^
 ffff8880a65a1700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880a65a1780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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