==================================================================
BUG: KASAN: slab-out-of-bounds in erspan_xmit+0x22d4/0x2430 net/ipv4/ip_gre.c:735
Read of size 2 at addr ffff8801c00b4acb by task syz-executor1/19258

CPU: 0 PID: 19258 Comm: syz-executor1 Not tainted 4.15.0-rc8+ #205
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+0x194/0x257 lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x25b/0x340 mm/kasan/report.c:409
 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/report.c:440
 erspan_xmit+0x22d4/0x2430 net/ipv4/ip_gre.c:735
 __netdev_start_xmit include/linux/netdevice.h:4055 [inline]
 netdev_start_xmit include/linux/netdevice.h:4064 [inline]
 packet_direct_xmit+0x3ad/0x790 net/packet/af_packet.c:267
 packet_snd net/packet/af_packet.c:2944 [inline]
 packet_sendmsg+0x3aed/0x60b0 net/packet/af_packet.c:2969
 sock_sendmsg_nosec net/socket.c:630 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:640
 SYSC_sendto+0x361/0x5c0 net/socket.c:1721
 SyS_sendto+0x40/0x50 net/socket.c:1689
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x452f19
RSP: 002b:00007f8b28ab4c58 EFLAGS: 00000212 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452f19
RDX: 0000000000000000 RSI: 0000000020011000 RDI: 0000000000000013
RBP: 000000000000059c R08: 0000000020008000 R09: 000000000000001c
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f7740
R13: 00000000ffffffff R14: 00007f8b28ab56d4 R15: 0000000000000000

Allocated by task 16583:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3544
 kmem_cache_zalloc include/linux/slab.h:678 [inline]
 ebitmap_cpy+0xce/0x260 security/selinux/ss/ebitmap.c:60
 mls_context_cpy security/selinux/ss/context.h:51 [inline]
 mls_compute_sid+0x555/0x930 security/selinux/ss/mls.c:556
 security_compute_sid+0x8df/0x18f0 security/selinux/ss/services.c:1724
 security_transition_sid+0x75/0x90 security/selinux/ss/services.c:1763
 socket_sockcreate_sid security/selinux/hooks.c:4335 [inline]
 selinux_socket_post_create+0x586/0x970 security/selinux/hooks.c:4386
 security_socket_post_create+0x8b/0xc0 security/security.c:1344
 __sock_create+0x6a4/0x850 net/socket.c:1275
 sock_create net/socket.c:1299 [inline]
 SYSC_socketpair net/socket.c:1387 [inline]
 SyS_socketpair+0x243/0x6f0 net/socket.c:1340
 entry_SYSCALL_64_fastpath+0x29/0xa0

Freed by task 16583:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3488 [inline]
 kmem_cache_free+0x83/0x2a0 mm/slab.c:3746
 ebitmap_destroy+0x79/0xe0 security/selinux/ss/ebitmap.c:338
 mls_context_destroy security/selinux/ss/context.h:109 [inline]
 context_destroy security/selinux/ss/context.h:148 [inline]
 security_compute_sid+0xa46/0x18f0 security/selinux/ss/services.c:1742
 security_transition_sid+0x75/0x90 security/selinux/ss/services.c:1763
 socket_sockcreate_sid security/selinux/hooks.c:4335 [inline]
 selinux_socket_post_create+0x586/0x970 security/selinux/hooks.c:4386
 security_socket_post_create+0x8b/0xc0 security/security.c:1344
 __sock_create+0x6a4/0x850 net/socket.c:1275
 sock_create net/socket.c:1299 [inline]
 SYSC_socketpair net/socket.c:1387 [inline]
 SyS_socketpair+0x243/0x6f0 net/socket.c:1340
 entry_SYSCALL_64_fastpath+0x29/0xa0

The buggy address belongs to the object at ffff8801c00b4a80
 which belongs to the cache ebitmap_node of size 64
The buggy address is located 11 bytes to the right of
 64-byte region [ffff8801c00b4a80, ffff8801c00b4ac0)
The buggy address belongs to the page:
page:ffffea0007002d00 count:1 mapcount:0 mapping:ffff8801c00b4000 index:0xffff8801c00b4e40
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801c00b4000 ffff8801c00b4e40 000000010000001c
raw: ffffea00072968a0 ffffea00074ee7a0 ffff8801d21fbc00 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c00b4980: fb fb fb fb fc fc fc fc fb fb fb fb fb fb fb fb
 ffff8801c00b4a00: fc fc fc fc fb fb fb fb fb fb fb fb fc fc fc fc
>ffff8801c00b4a80: fb fb fb fb fb fb fb fb fc fc fc fc fb fb fb fb
                                              ^
 ffff8801c00b4b00: fb fb fb fb fc fc fc fc fb fb fb fb fb fb fb fb
 ffff8801c00b4b80: fc fc fc fc fb fb fb fb fb fb fb fb fc fc fc fc
==================================================================