audit: type=1400 audit(1549511277.802:22424): avc: denied { syslog } for pid=17923 comm="syz-executor3" capability=34 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=capability2 permissive=1 ================================================================== 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 ffff8881d2355a9c by task syz-executor0/17939 CPU: 0 PID: 17939 Comm: syz-executor0 Not tainted 4.14.97+ #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 17939: 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 dev_queue_xmit_nit+0x2f3/0x960 net/core/dev.c:1943 xmit_one net/core/dev.c:3005 [inline] dev_hard_start_xmit+0xa3/0x890 net/core/dev.c:3025 sch_direct_xmit+0x27a/0x520 net/sched/sch_generic.c:186 Freed by task 17939: 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 dev_queue_xmit_nit+0x6d0/0x960 net/core/dev.c:1975 The buggy address belongs to the object at ffff8881d2355a00 which belongs to the cache skbuff_head_cache of size 224 The buggy address is located 156 bytes inside of 224-byte region [ffff8881d2355a00, ffff8881d2355ae0) The buggy address belongs to the page: page:ffffea000748d540 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: ffff8881d2355980: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc ffff8881d2355a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881d2355a80: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff8881d2355b00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ffff8881d2355b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================