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BUG: KMSAN: use-after-free in fib6_nh_flush_exceptions net/ipv6/route.c:1724 [inline]
BUG: KMSAN: use-after-free in fib6_nh_release+0x304/0x6b0 net/ipv6/route.c:3505
CPU: 1 PID: 18655 Comm: syz-executor.5 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c9/0x220 lib/dump_stack.c:118
 kmsan_report+0xf8/0x1e0 mm/kmsan/kmsan_report.c:118
 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
 fib6_nh_flush_exceptions net/ipv6/route.c:1724 [inline]
 fib6_nh_release+0x304/0x6b0 net/ipv6/route.c:3505
 fib6_info_destroy_rcu+0x18b/0x330 net/ipv6/ip6_fib.c:174
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch kernel/rcu/tree.c:2183 [inline]
 rcu_core+0xc76/0x1b10 kernel/rcu/tree.c:2408
 rcu_core_si+0xe/0x10 kernel/rcu/tree.c:2417
 __do_softirq+0x4a1/0x83a kernel/softirq.c:293
 do_softirq_own_stack+0x49/0x80 arch/x86/entry/entry_64.S:1091
 </IRQ>
 do_softirq kernel/softirq.c:338 [inline]
 __local_bh_enable_ip+0x184/0x1d0 kernel/softirq.c:190
 local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32
 get_next_corpse net/netfilter/nf_conntrack_core.c:2011 [inline]
 nf_ct_iterate_cleanup+0x596/0x6f0 net/netfilter/nf_conntrack_core.c:2034
 nf_ct_iterate_cleanup_net+0x182/0x230 net/netfilter/nf_conntrack_core.c:2119
 masq_device_event+0x10c/0x180 net/netfilter/nf_nat_masquerade.c:88
 notifier_call_chain kernel/notifier.c:83 [inline]
 __raw_notifier_call_chain kernel/notifier.c:361 [inline]
 raw_notifier_call_chain+0x13d/0x240 kernel/notifier.c:368
 call_netdevice_notifiers_info net/core/dev.c:1893 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:1905 [inline]
 call_netdevice_notifiers net/core/dev.c:1919 [inline]
 dev_close_many+0x660/0xad0 net/core/dev.c:1544
 rollback_registered_many+0x91b/0x28b0 net/core/dev.c:8721
 unregister_netdevice_many+0x79/0x5e0 net/core/dev.c:9907
 rtnl_delete_link net/core/rtnetlink.c:2928 [inline]
 rtnl_dellink+0xa1d/0x12a0 net/core/rtnetlink.c:2980
 rtnetlink_rcv_msg+0x115a/0x1580 net/core/rtnetlink.c:5424
 netlink_rcv_skb+0x431/0x620 net/netlink/af_netlink.c:2477
 rtnetlink_rcv+0x50/0x60 net/core/rtnetlink.c:5442
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0xfa0/0x1100 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x11f0/0x1480 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:639 [inline]
 sock_sendmsg net/socket.c:659 [inline]
 ____sys_sendmsg+0x1362/0x13f0 net/socket.c:2330
 ___sys_sendmsg net/socket.c:2384 [inline]
 __sys_sendmsg+0x4f0/0x5e0 net/socket.c:2417
 __do_sys_sendmsg net/socket.c:2426 [inline]
 __se_sys_sendmsg+0x97/0xb0 net/socket.c:2424
 __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2424
 do_syscall_64+0xb6/0x160 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45a919
Code: ad b6 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f7158ae8c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a919
RDX: 0000000000000000 RSI: 0000000020000380 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f7158ae96d4
R13: 00000000004c92d0 R14: 00000000004e1028 R15: 00000000ffffffff

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
 kmsan_internal_poison_shadow+0x5c/0xf0 mm/kmsan/kmsan.c:127
 kmsan_slab_free+0x6e/0xb0 mm/kmsan/kmsan_hooks.c:107
 slab_free_freelist_hook mm/slub.c:1458 [inline]
 slab_free mm/slub.c:3021 [inline]
 kfree+0x8ce/0x3090 mm/slub.c:3974
 free_pipe_info+0x421/0x440 fs/pipe.c:801
 put_pipe_info fs/pipe.c:672 [inline]
 pipe_release+0x40e/0x530 fs/pipe.c:693
 __fput+0x4c9/0xba0 fs/file_table.c:280
 ____fput+0x37/0x40 fs/file_table.c:313
 task_work_run+0x22e/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:164 [inline]
 prepare_exit_to_usermode+0x3cf/0x530 arch/x86/entry/common.c:195
 syscall_return_slowpath+0x90/0x610 arch/x86/entry/common.c:278
 do_syscall_64+0xdc/0x160 arch/x86/entry/common.c:306
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
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