audit: type=1400 audit(1569562015.377:8): avc:  denied  { prog_load } for  pid=1793 comm="syz-executor263" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=bpf permissive=1
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audit: type=1400 audit(1569562015.427:9): avc:  denied  { prog_run } for  pid=1793 comm="syz-executor263" scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=bpf permissive=1
BUG: KASAN: slab-out-of-bounds in ____bpf_skb_change_head net/core/filter.c:2423 [inline]
BUG: KASAN: slab-out-of-bounds in bpf_skb_change_head+0x4ea/0x600 net/core/filter.c:2419
Read of size 4 at addr ffff8881cbeb2878 by task syz-executor263/1793

CPU: 0 PID: 1793 Comm: syz-executor263 Not tainted 4.14.146+ #0
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xca/0x134 lib/dump_stack.c:53
 print_address_description+0x60/0x226 mm/kasan/report.c:187
 __kasan_report.cold+0x1a/0x41 mm/kasan/report.c:316
 ____bpf_skb_change_head net/core/filter.c:2423 [inline]
 bpf_skb_change_head+0x4ea/0x600 net/core/filter.c:2419
 ___bpf_prog_run+0x2478/0x5510 kernel/bpf/core.c:1095

Allocated by task 222:
 save_stack mm/kasan/common.c:76 [inline]
 set_track mm/kasan/common.c:85 [inline]
 __kasan_kmalloc.part.0+0x53/0xc0 mm/kasan/common.c:501
 slab_post_alloc_hook mm/slab.h:439 [inline]
 slab_alloc_node mm/slub.c:2792 [inline]
 slab_alloc mm/slub.c:2800 [inline]
 kmem_cache_alloc+0xee/0x360 mm/slub.c:2805
 kmem_cache_alloc_node include/linux/slab.h:361 [inline]
 __alloc_skb+0xea/0x5c0 net/core/skbuff.c:193
 alloc_skb include/linux/skbuff.h:980 [inline]
 netlink_alloc_large_skb net/netlink/af_netlink.c:1158 [inline]
 netlink_sendmsg+0x958/0xbe0 net/netlink/af_netlink.c:1852
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb7/0x100 net/socket.c:656
 ___sys_sendmsg+0x752/0x890 net/socket.c:2062
 __sys_sendmsg+0xb6/0x150 net/socket.c:2096
 SYSC_sendmsg net/socket.c:2107 [inline]
 SyS_sendmsg+0x27/0x40 net/socket.c:2103
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
 0xffffffffffffffff

Freed by task 222:
 save_stack mm/kasan/common.c:76 [inline]
 set_track mm/kasan/common.c:85 [inline]
 __kasan_slab_free+0x164/0x210 mm/kasan/common.c:463
 slab_free_hook mm/slub.c:1407 [inline]
 slab_free_freelist_hook mm/slub.c:1458 [inline]
 slab_free mm/slub.c:3039 [inline]
 kmem_cache_free+0xd7/0x3b0 mm/slub.c:3055
 kfree_skbmem net/core/skbuff.c:586 [inline]
 kfree_skbmem+0xa0/0x110 net/core/skbuff.c:580
 __kfree_skb net/core/skbuff.c:646 [inline]
 kfree_skb+0xeb/0x370 net/core/skbuff.c:663
 netlink_unicast_kernel net/netlink/af_netlink.c:1289 [inline]
 netlink_unicast+0x595/0x650 net/netlink/af_netlink.c:1312
 netlink_sendmsg+0x66a/0xbe0 net/netlink/af_netlink.c:1877
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb7/0x100 net/socket.c:656
 ___sys_sendmsg+0x752/0x890 net/socket.c:2062
 __sys_sendmsg+0xb6/0x150 net/socket.c:2096
 SYSC_sendmsg net/socket.c:2107 [inline]
 SyS_sendmsg+0x27/0x40 net/socket.c:2103
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
 0xffffffffffffffff

The buggy address belongs to the object at ffff8881cbeb2780
 which belongs to the cache skbuff_head_cache of size 224
The buggy address is located 24 bytes to the right of
 224-byte region [ffff8881cbeb2780, ffff8881cbeb2860)
The buggy address belongs to the page:
page:ffffea00072fac80 count:1 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000200(slab)
raw: 4000000000000200 0000000000000000 0000000000000000 00000001800c000c
raw: ffffea00072fda40 0000000200000002 ffff8881d6770200 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881cbeb2700: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881cbeb2780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881cbeb2800: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                                                                ^
 ffff8881cbeb2880: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff8881cbeb2900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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