==================================================================
BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:199 [inline]
BUG: KASAN: use-after-free in __in6_dev_get include/net/addrconf.h:309 [inline]
BUG: KASAN: use-after-free in ip6_ignore_linkdown include/net/addrconf.h:400 [inline]
BUG: KASAN: use-after-free in find_match+0xb39/0xc90 net/ipv6/route.c:749
Read of size 8 at addr ffff88809fa68320 by task swapper/0/0

CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-rc2-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+0x197/0x210 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:641
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
 __read_once_size include/linux/compiler.h:199 [inline]
 __in6_dev_get include/net/addrconf.h:309 [inline]
 ip6_ignore_linkdown include/net/addrconf.h:400 [inline]
 find_match+0xb39/0xc90 net/ipv6/route.c:749
 __find_rr_leaf+0x14e/0x750 net/ipv6/route.c:837
 find_rr_leaf net/ipv6/route.c:858 [inline]
 rt6_select net/ipv6/route.c:902 [inline]
 fib6_table_lookup+0x697/0xdb0 net/ipv6/route.c:2170
 ip6_pol_route+0x1f6/0xa70 net/ipv6/route.c:2206
 ip6_pol_route_input+0x65/0x80 net/ipv6/route.c:2264
 fib6_rule_lookup+0x133/0x7d0 net/ipv6/fib6_rules.c:114
 ip6_route_input_lookup+0xb7/0xd0 net/ipv6/route.c:2276
 ip6_route_input+0x5f0/0xa40 net/ipv6/route.c:2445
 ip6_rcv_finish_core.isra.0+0x174/0x590 net/ipv6/ip6_input.c:63
 ip6_rcv_finish+0x17a/0x310 net/ipv6/ip6_input.c:74
 NF_HOOK include/linux/netfilter.h:307 [inline]
 NF_HOOK include/linux/netfilter.h:301 [inline]
 ipv6_rcv+0x10e/0x420 net/ipv6/ip6_input.c:306
 __netif_receive_skb_one_core+0x113/0x1a0 net/core/dev.c:5198
 __netif_receive_skb+0x2c/0x1d0 net/core/dev.c:5312
 process_backlog+0x226/0x780 net/core/dev.c:6144
 napi_poll net/core/dev.c:6582 [inline]
 net_rx_action+0x508/0x1120 net/core/dev.c:6650
 __do_softirq+0x262/0x98c kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x19b/0x1e0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:546 [inline]
 smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1146
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
Code: 08 f2 c4 f9 eb 8a cc cc cc cc cc cc e9 07 00 00 00 0f 00 2d 04 3a 59 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d f4 39 59 00 fb f4 <c3> cc 55 48 89 e5 41 57 41 56 41 55 41 54 53 e8 7e a9 73 f9 e8 19
RSP: 0018:ffffffff89a07ce8 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff136761a RBX: ffffffff89a7a440 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffffffff89a7acd4
RBP: ffffffff89a07d18 R08: ffffffff89a7a440 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
R13: ffffffff8aa5a680 R14: 0000000000000000 R15: 0000000000000000
 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:686
 default_idle_call+0x84/0xb0 kernel/sched/idle.c:94
 cpuidle_idle_call kernel/sched/idle.c:154 [inline]
 do_idle+0x3c8/0x6e0 kernel/sched/idle.c:269
 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:361
 rest_init+0x23b/0x371 init/main.c:654
 arch_call_rest_init+0xe/0x1b
 start_kernel+0x886/0x8c5 init/main.c:992
 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:490
 x86_64_start_kernel+0x77/0x7b arch/x86/kernel/head64.c:471
 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

Allocated by task 9887:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc mm/kasan/common.c:515 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:488
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529
 __do_kmalloc_node mm/slab.c:3616 [inline]
 __kmalloc_node+0x4e/0x70 mm/slab.c:3623
 kmalloc_node include/linux/slab.h:578 [inline]
 kvmalloc_node+0x68/0x100 mm/util.c:574
 kvmalloc include/linux/mm.h:645 [inline]
 kvzalloc include/linux/mm.h:653 [inline]
 alloc_netdev_mqs+0x98/0xe40 net/core/dev.c:9797
 vti6_init_net+0x244/0x810 net/ipv6/ip6_vti.c:1119
 ops_init+0xb3/0x420 net/core/net_namespace.c:137
 setup_net+0x2d5/0x8b0 net/core/net_namespace.c:327
 copy_net_ns+0x29e/0x5a0 net/core/net_namespace.c:468
 create_new_namespaces+0x403/0xb50 kernel/nsproxy.c:108
 unshare_nsproxy_namespaces+0xc2/0x200 kernel/nsproxy.c:229
 ksys_unshare+0x444/0x980 kernel/fork.c:2955
 __do_sys_unshare kernel/fork.c:3023 [inline]
 __se_sys_unshare kernel/fork.c:3021 [inline]
 __x64_sys_unshare+0x31/0x40 kernel/fork.c:3021
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9887:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:337 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:476
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3757
 __netdev_name_node_alt_destroy+0x1ff/0x2a0 net/core/dev.c:322
 netdev_name_node_alt_destroy+0x57/0x80 net/core/dev.c:334
 rtnl_alt_ifname net/core/rtnetlink.c:3518 [inline]
 rtnl_linkprop.isra.0+0x575/0x6f0 net/core/rtnetlink.c:3567
 rtnl_dellinkprop+0x46/0x60 net/core/rtnetlink.c:3588
 rtnetlink_rcv_msg+0x45e/0xaf0 net/core/rtnetlink.c:5438
 netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2477
 rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5456
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0x59e/0x7e0 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x91c/0xea0 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:672
 ____sys_sendmsg+0x753/0x880 net/socket.c:2343
 ___sys_sendmsg+0x100/0x170 net/socket.c:2397
 __sys_sendmsg+0x105/0x1d0 net/socket.c:2430
 __do_sys_sendmsg net/socket.c:2439 [inline]
 __se_sys_sendmsg net/socket.c:2437 [inline]
 __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2437
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88809fa68000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 800 bytes inside of
 4096-byte region [ffff88809fa68000, ffff88809fa69000)
The buggy address belongs to the page:
page:ffffea00027e9a00 refcount:1 mapcount:0 mapping:ffff8880aa402000 index:0x0 compound_mapcount: 0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea0002871508 ffffea0002a0f288 ffff8880aa402000
raw: 0000000000000000 ffff88809fa68000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809fa68200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809fa68280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88809fa68300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff88809fa68380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809fa68400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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