==================================================================
BUG: KASAN: use-after-free in ex_handler_refcount+0x18f/0x1c0 arch/x86/mm/extable.c:49
Write of size 4 at addr ffff88809d2b4c00 by task kworker/0:1/4932

CPU: 0 PID: 4932 Comm: kworker/0:1 Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events sco_sock_timeout
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
 print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
 kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354
 kasan_report mm/kasan/report.c:412 [inline]
 __asan_report_store4_noabort+0x88/0x90 mm/kasan/report.c:437
 ex_handler_refcount+0x18f/0x1c0 arch/x86/mm/extable.c:49
 fixup_exception+0x8a/0xd0 arch/x86/mm/extable.c:197
 do_trap_no_signal arch/x86/kernel/traps.c:209 [inline]
 do_trap+0x61/0x250 arch/x86/kernel/traps.c:258
 do_error_trap+0x15d/0x310 arch/x86/kernel/traps.c:303
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1038
RIP: 0010:__noinstr_text_end+0x60f9/0x7813
Code: 8d 80 00 00 00 0f 0b 49 8d 8d e4 00 00 00 0f 0b 49 8d 8d 80 00 00 00 0f 0b 49 8d 8c 24 80 00 00 00 0f 0b 48 8d 8d 80 00 00 00 <0f> 0b 48 8d 8d 80 00 00 00 0f 0b 49 8d 8c 24 80 00 00 00 0f 0b 49
RSP: 0018:ffff88807fb8fd28 EFLAGS: 00010283
RAX: ffff888098758300 RBX: 0000000000000000 RCX: ffff88809d2b4c00
RDX: 0000000000000000 RSI: ffffffff87462a68 RDI: ffff8880a9cdf700
RBP: ffff88809d2b4b80 R08: 0000000000000001 R09: ffffed101539bed9
R10: ffff8880a9cdf6cb R11: 0000000000074071 R12: ffff8880a9cdf6c8
R13: ffff8880a93c2300 R14: ffff8880ba02a8c0 R15: ffff8880ba02f000
 process_one_work+0x864/0x1570 kernel/workqueue.c:2153
 worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
 kthread+0x33f/0x460 kernel/kthread.c:259
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415

Allocated by task 18502:
 __do_kmalloc mm/slab.c:3727 [inline]
 __kmalloc+0x15a/0x3c0 mm/slab.c:3736
 kmalloc include/linux/slab.h:520 [inline]
 kzalloc include/linux/slab.h:709 [inline]
 __register_sysctl_table+0x112/0x1090 fs/proc/proc_sysctl.c:1310
 __devinet_sysctl_register+0x156/0x280 net/ipv4/devinet.c:2344
 devinet_sysctl_register+0x160/0x230 net/ipv4/devinet.c:2384
 inetdev_init+0x223/0x4a0 net/ipv4/devinet.c:269
 inetdev_event+0x9cf/0x1270 net/ipv4/devinet.c:1477
 notifier_call_chain+0xc0/0x230 kernel/notifier.c:93
 call_netdevice_notifiers net/core/dev.c:1762 [inline]
 register_netdevice+0xdd2/0x10f0 net/core/dev.c:8761
 register_netdev+0x2d/0x50 net/core/dev.c:8859
 ip6_tnl_init_net+0x501/0x800 net/ipv6/ip6_tunnel.c:2264
 ops_init+0xb3/0x410 net/core/net_namespace.c:129
 setup_net+0x2c2/0x720 net/core/net_namespace.c:316
 copy_net_ns+0x1f7/0x340 net/core/net_namespace.c:439
 create_new_namespaces+0x3f6/0x7b0 kernel/nsproxy.c:107
 unshare_nsproxy_namespaces+0xbd/0x1f0 kernel/nsproxy.c:206
 ksys_unshare+0x36c/0x9a0 kernel/fork.c:2542
 __do_sys_unshare kernel/fork.c:2610 [inline]
 __se_sys_unshare kernel/fork.c:2608 [inline]
 __x64_sys_unshare+0x2d/0x40 kernel/fork.c:2608
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9:
 __cache_free mm/slab.c:3503 [inline]
 kfree+0xcc/0x210 mm/slab.c:3822
 __rcu_reclaim kernel/rcu/rcu.h:231 [inline]
 rcu_do_batch kernel/rcu/tree.c:2584 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2897 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2864 [inline]
 rcu_process_callbacks+0xa0d/0x18b0 kernel/rcu/tree.c:2881
 __do_softirq+0x265/0x980 kernel/softirq.c:292

The buggy address belongs to the object at ffff88809d2b4b80
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 128 bytes inside of
 2048-byte region [ffff88809d2b4b80, ffff88809d2b5380)
The buggy address belongs to the page:
page:ffffea000274ad00 count:1 mapcount:0 mapping:ffff88813bff0c40 index:0x0 compound_mapcount: 0
flags: 0xfff00000008100(slab|head)
raw: 00fff00000008100 ffffea0001c7bd08 ffffea0001c70e08 ffff88813bff0c40
raw: 0000000000000000 ffff88809d2b4300 0000000100000003 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809d2b4b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809d2b4b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88809d2b4c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88809d2b4c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809d2b4d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================