IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
8021q: adding VLAN 0 to HW filter on device batadv0
==================================================================
BUG: KASAN: use-after-free in erspan_build_header+0x392/0x3b0 net/ipv4/ip_gre.c:706
Read of size 2 at addr ffff8880a4fb568b by task syz-executor201/7088

CPU: 1 PID: 7088 Comm: syz-executor201 Not tainted 4.14.111 #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x138/0x19c lib/dump_stack.c:53
 print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xaf/0x2b5 mm/kasan/report.c:393
 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/report.c:440
 erspan_build_header+0x392/0x3b0 net/ipv4/ip_gre.c:706
 erspan_xmit net/ipv4/ip_gre.c:748 [inline]
 erspan_xmit+0x3ec/0x11c0 net/ipv4/ip_gre.c:725
 __netdev_start_xmit include/linux/netdevice.h:4033 [inline]
 netdev_start_xmit include/linux/netdevice.h:4042 [inline]
 packet_direct_xmit+0x438/0x640 net/packet/af_packet.c:269
 packet_snd net/packet/af_packet.c:2969 [inline]
 packet_sendmsg+0x31e1/0x5990 net/packet/af_packet.c:2994
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xd0/0x110 net/socket.c:656
 SYSC_sendto+0x206/0x310 net/socket.c:1763
 SyS_sendto+0x40/0x50 net/socket.c:1731
 do_syscall_64+0x1eb/0x630 arch/x86/entry/common.c:289
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x442249
RSP: 002b:00007ffc99a67dc8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000442249
RDX: 000000000000000e RSI: 0000000020000180 RDI: 0000000000000003
RBP: 00000000004a9450 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000403150
R13: 00000000004031e0 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea000293ed40 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x1fffc0000000000()
raw: 01fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 0000000100000001 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a4fb5580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880a4fb5600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880a4fb5680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                      ^
 ffff8880a4fb5700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880a4fb5780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================