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BUG: KASAN: use-after-free in ____bpf_clone_redirect net/core/filter.c:1768 [inline]
BUG: KASAN: use-after-free in bpf_clone_redirect+0x2a7/0x2b0 net/core/filter.c:1759
Read of size 8 at addr ffff8881a6e62850 by task syz-executor.5/9514

CPU: 1 PID: 9514 Comm: syz-executor.5 Not tainted 4.14.150+ #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_clone_redirect net/core/filter.c:1768 [inline]
 bpf_clone_redirect+0x2a7/0x2b0 net/core/filter.c:1759
 ___bpf_prog_run+0x2478/0x5510 kernel/bpf/core.c:1095

Allocated by task 8451:
 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]
 alloc_skb_with_frags+0x85/0x500 net/core/skbuff.c:5228
 sock_alloc_send_pskb+0x5c9/0x720 net/core/sock.c:2078
 __ip_append_data.isra.0+0xfae/0x2060 net/ipv4/ip_output.c:972
 ip_make_skb+0x1a0/0x1f0 net/ipv4/ip_output.c:1485
 udp_sendmsg+0x157a/0x1bb0 net/ipv4/udp.c:1052
 inet_sendmsg+0x15b/0x520 net/ipv4/af_inet.c:760
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb7/0x100 net/socket.c:656
 ___sys_sendmsg+0x368/0x890 net/socket.c:2062
 __sys_sendmmsg+0x13c/0x360 net/socket.c:2152
 SYSC_sendmmsg net/socket.c:2183 [inline]
 SyS_sendmmsg+0x2f/0x50 net/socket.c:2178
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
 0xffffffffffffffff

Freed by task 8480:
 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]
 consume_skb+0xe4/0x360 net/core/skbuff.c:705
 tun_do_read+0x508/0x13b0 drivers/net/tun.c:1770
 tun_chr_read_iter+0xd9/0x1c0 drivers/net/tun.c:1784
 call_read_iter include/linux/fs.h:1792 [inline]
 new_sync_read fs/read_write.c:401 [inline]
 __vfs_read+0x3fe/0x590 fs/read_write.c:413
 vfs_read+0x131/0x330 fs/read_write.c:447
 SYSC_read fs/read_write.c:578 [inline]
 SyS_read+0x102/0x250 fs/read_write.c:571
 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 ffff8881a6e62780
 which belongs to the cache skbuff_head_cache of size 224
The buggy address is located 208 bytes inside of
 224-byte region [ffff8881a6e62780, ffff8881a6e62860)
The buggy address belongs to the page:
page:ffffea00069b9880 count:1 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000200(slab)
raw: 4000000000000200 0000000000000000 0000000000000000 00000001800c000c
raw: ffffea00068970c0 0000000800000008 ffff8881dab70200 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881a6e62700: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881a6e62780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8881a6e62800: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                                                 ^
 ffff8881a6e62880: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
 ffff8881a6e62900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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