audit: type=1400 audit(1547062927.513:9): avc:  denied  { map } for  pid=1785 comm="syz-execprog" path="/root/syzkaller-shm731214131" dev="sda1" ino=16482 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:file_t:s0 tclass=file permissive=1
hrtimer: interrupt took 27445 ns
syz-executor4 (2473) used greatest stack depth: 24400 bytes left
==================================================================
BUG: KASAN: use-after-free in skb_clear_hash include/linux/skbuff.h:1128 [inline]
BUG: KASAN: use-after-free in ip_check_defrag net/ipv4/ip_fragment.c:747 [inline]
BUG: KASAN: use-after-free in ip_check_defrag+0x4f5/0x523 net/ipv4/ip_fragment.c:712
Write of size 4 at addr ffff8881c93d031c by task syz-executor0/3032

CPU: 1 PID: 3032 Comm: syz-executor0 Not tainted 4.14.92+ #4
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xb9/0x10e lib/dump_stack.c:53
 print_address_description+0x60/0x226 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+0x88/0x2a5 mm/kasan/report.c:393

Allocated by task 3032:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc.part.0+0x4f/0xd0 mm/kasan/kasan.c:551
 slab_post_alloc_hook mm/slab.h:442 [inline]
 slab_alloc_node mm/slub.c:2723 [inline]
 slab_alloc mm/slub.c:2731 [inline]
 kmem_cache_alloc+0xd2/0x2d0 mm/slub.c:2736
 skb_clone+0x126/0x310 net/core/skbuff.c:1278
 skb_share_check include/linux/skbuff.h:1538 [inline]
 ip_check_defrag net/ipv4/ip_fragment.c:734 [inline]
 ip_check_defrag+0x2bc/0x523 net/ipv4/ip_fragment.c:712
 packet_rcv_fanout+0x4d1/0x5e0 net/packet/af_packet.c:1463
 deliver_skb net/core/dev.c:1881 [inline]
 dev_queue_xmit_nit+0x21a/0x960 net/core/dev.c:1937

Freed by task 3032:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xb0/0x190 mm/kasan/kasan.c:524
 slab_free_hook mm/slub.c:1389 [inline]
 slab_free_freelist_hook mm/slub.c:1410 [inline]
 slab_free mm/slub.c:2966 [inline]
 kmem_cache_free+0xc4/0x330 mm/slub.c:2988
 kfree_skbmem net/core/skbuff.c:582 [inline]
 kfree_skbmem+0xa0/0x100 net/core/skbuff.c:576
 __kfree_skb net/core/skbuff.c:642 [inline]
 kfree_skb+0xcd/0x350 net/core/skbuff.c:659
 ip_frag_queue net/ipv4/ip_fragment.c:507 [inline]
 ip_defrag+0x5f4/0x3b50 net/ipv4/ip_fragment.c:699
 ip_check_defrag net/ipv4/ip_fragment.c:745 [inline]
 ip_check_defrag+0x39b/0x523 net/ipv4/ip_fragment.c:712
 packet_rcv_fanout+0x4d1/0x5e0 net/packet/af_packet.c:1463
 deliver_skb net/core/dev.c:1881 [inline]
 dev_queue_xmit_nit+0x21a/0x960 net/core/dev.c:1937

The buggy address belongs to the object at ffff8881c93d0280
 which belongs to the cache skbuff_head_cache of size 224
The buggy address is located 156 bytes inside of
 224-byte region [ffff8881c93d0280, ffff8881c93d0360)
The buggy address belongs to the page:
page:ffffea000724f400 count:1 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000100(slab)
raw: 4000000000000100 0000000000000000 0000000000000000 00000001800c000c
raw: dead000000000100 dead000000000200 ffff8881dab58200 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881c93d0200: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881c93d0280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881c93d0300: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                            ^
 ffff8881c93d0380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881c93d0400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================