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BUG: KASAN: null-ptr-deref in fib6_drop_pcpu_from net/ipv6/ip6_fib.c:925 [inline]
BUG: KASAN: null-ptr-deref in fib6_purge_rt+0x1b3/0x5e0 net/ipv6/ip6_fib.c:937
Write of size 8 at addr 0000000000000239 by task syz-executor.5/18563

CPU: 0 PID: 18563 Comm: syz-executor.5 Not tainted 5.2.0-rc1+ #34
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 __kasan_report.cold+0x5/0x40 mm/kasan/report.c:321
 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:8159
 rollback_registered+0x109/0x1d0 net/core/dev.c:8224
 unregister_netdevice_queue net/core/dev.c:9271 [inline]
 unregister_netdevice_queue+0x1ee/0x2c0 net/core/dev.c:9264
 unregister_netdevice include/linux/netdevice.h:2635 [inline]
 __tun_detach+0xd8a/0x1040 drivers/net/tun.c:733
 tun_detach drivers/net/tun.c:750 [inline]
 tun_chr_close+0xe0/0x180 drivers/net/tun.c:3460
 __fput+0x2ff/0x890 fs/file_table.c:280
 ____fput+0x16/0x20 fs/file_table.c:313
 task_work_run+0x145/0x1c0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x90a/0x2fa0 kernel/exit.c:877
 do_group_exit+0x135/0x370 kernel/exit.c:981
 __do_sys_exit_group kernel/exit.c:992 [inline]
 __se_sys_exit_group kernel/exit.c:990 [inline]
 __x64_sys_exit_group+0x44/0x50 kernel/exit.c:990
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459279
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd2805ea58 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 000000000000001c RCX: 0000000000459279
RDX: 0000000000412e80 RSI: 0000000000a74ef0 RDI: 0000000000000043
RBP: 00000000004be9d7 R08: 000000000000000c R09: 000000000028db8f
R10: 00005555565b5940 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00007ffd2805eba0 R14: 000000000028dafb R15: 00007ffd2805ebb0
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