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BUG: KASAN: slab-out-of-bounds in skb_headlen include/linux/skbuff.h:1893 [inline]
BUG: KASAN: slab-out-of-bounds in pskb_may_pull include/linux/skbuff.h:2107 [inline]
BUG: KASAN: slab-out-of-bounds in skb_ensure_writable+0x290/0x2e0 net/core/skbuff.c:5001
Read of size 4 at addr ffff88016cf685f8 by task syz-executor6/5472

CPU: 1 PID: 5472 Comm: syz-executor6 Not tainted 4.14.68+ #4
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xb9/0x11b lib/dump_stack.c:53
 print_address_description+0x60/0x22b mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report.cold.6+0x11b/0x2dd mm/kasan/report.c:409
 skb_headlen include/linux/skbuff.h:1893 [inline]
 pskb_may_pull include/linux/skbuff.h:2107 [inline]
 skb_ensure_writable+0x290/0x2e0 net/core/skbuff.c:5001
 __bpf_try_make_writable net/core/filter.c:1403 [inline]
 bpf_try_make_writable net/core/filter.c:1409 [inline]
 ____bpf_l4_csum_replace net/core/filter.c:1578 [inline]
 bpf_l4_csum_replace+0x61/0x300 net/core/filter.c:1565
 ___bpf_prog_run+0x248e/0x5c70 kernel/bpf/core.c:1012

Allocated by task 3181:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc.part.1+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+0xe4/0x2b0 mm/slub.c:2736
 skb_clone+0x120/0x300 net/core/skbuff.c:1281
 dev_queue_xmit_nit+0x2f8/0x960 net/core/dev.c:1921
 xmit_one net/core/dev.c:2983 [inline]
 dev_hard_start_xmit+0xa2/0x890 net/core/dev.c:3003
 sch_direct_xmit+0x280/0x520 net/sched/sch_generic.c:186
 __dev_xmit_skb net/core/dev.c:3196 [inline]
 __dev_queue_xmit+0x16fd/0x1f40 net/core/dev.c:3471
 neigh_hh_output include/net/neighbour.h:472 [inline]
 neigh_output include/net/neighbour.h:480 [inline]
 ip_finish_output2+0xc56/0x1190 net/ipv4/ip_output.c:229
 ip_finish_output+0x3a5/0xc40 net/ipv4/ip_output.c:317
 NF_HOOK_COND include/linux/netfilter.h:239 [inline]
 ip_mc_output+0x234/0xc20 net/ipv4/ip_output.c:390
 dst_output include/net/dst.h:459 [inline]
 ip_local_out+0x94/0x170 net/ipv4/ip_output.c:124
 ip_send_skb+0x37/0xb0 net/ipv4/ip_output.c:1417
 udp_send_skb+0x533/0xb90 net/ipv4/udp.c:829
 udp_sendmsg+0x16ce/0x1da0 net/ipv4/udp.c:1053
 inet_sendmsg+0x168/0x540 net/ipv4/af_inet.c:781
 sock_sendmsg_nosec net/socket.c:645 [inline]
 sock_sendmsg+0xb5/0x100 net/socket.c:655
 ___sys_sendmsg+0x41d/0x890 net/socket.c:2061
 __sys_sendmmsg+0x13d/0x360 net/socket.c:2151
 SYSC_sendmmsg net/socket.c:2182 [inline]
 SyS_sendmmsg+0x2f/0x50 net/socket.c:2177
 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 3181:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xac/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+0x12d/0x350 mm/slub.c:2988
 kfree_skbmem+0x9e/0x100 net/core/skbuff.c:582
 __kfree_skb net/core/skbuff.c:642 [inline]
 consume_skb+0xc9/0x330 net/core/skbuff.c:701
 packet_rcv+0xdd/0x11f0 net/packet/af_packet.c:2178
 dev_queue_xmit_nit+0x6e6/0x960 net/core/dev.c:1953
 xmit_one net/core/dev.c:2983 [inline]
 dev_hard_start_xmit+0xa2/0x890 net/core/dev.c:3003
 sch_direct_xmit+0x280/0x520 net/sched/sch_generic.c:186
 __dev_xmit_skb net/core/dev.c:3196 [inline]
 __dev_queue_xmit+0x16fd/0x1f40 net/core/dev.c:3471
 neigh_hh_output include/net/neighbour.h:472 [inline]
 neigh_output include/net/neighbour.h:480 [inline]
 ip_finish_output2+0xc56/0x1190 net/ipv4/ip_output.c:229
 ip_finish_output+0x3a5/0xc40 net/ipv4/ip_output.c:317
 NF_HOOK_COND include/linux/netfilter.h:239 [inline]
 ip_mc_output+0x234/0xc20 net/ipv4/ip_output.c:390
 dst_output include/net/dst.h:459 [inline]
 ip_local_out+0x94/0x170 net/ipv4/ip_output.c:124
 ip_send_skb+0x37/0xb0 net/ipv4/ip_output.c:1417
 udp_send_skb+0x533/0xb90 net/ipv4/udp.c:829
 udp_sendmsg+0x16ce/0x1da0 net/ipv4/udp.c:1053
 inet_sendmsg+0x168/0x540 net/ipv4/af_inet.c:781
 sock_sendmsg_nosec net/socket.c:645 [inline]
 sock_sendmsg+0xb5/0x100 net/socket.c:655
 ___sys_sendmsg+0x41d/0x890 net/socket.c:2061
 __sys_sendmmsg+0x13d/0x360 net/socket.c:2151
 SYSC_sendmmsg net/socket.c:2182 [inline]
 SyS_sendmmsg+0x2f/0x50 net/socket.c:2177
 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff88016cf68500
 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 [ffff88016cf68500, ffff88016cf685e0)
The buggy address belongs to the page:
page:ffffea0005b3da00 count:1 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000100(slab)
raw: 4000000000000100 0000000000000000 0000000000000000 00000001800c000c
raw: 0000000000000000 0000000b00000001 ffff8801da312200 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88016cf68480: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88016cf68500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88016cf68580: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                                                                ^
 ffff88016cf68600: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff88016cf68680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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