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BUG: KASAN: use-after-free in tcp_connect+0x26c2/0x30b0 net/ipv4/tcp_output.c:3417
Read of size 4 at addr ffff8801d7294028 by task syz-executor.5/1999

CPU: 1 PID: 1999 Comm: syz-executor.5 Not tainted 4.9.181+ #6
 ffff88017f277998 ffffffff81b57db1 0000000000000000 ffffea00075ca500
 ffff8801d7294028 0000000000000004 ffffffff82528622 ffff88017f2779d0
 ffffffff8150ab78 0000000000000000 ffff8801d7294028 ffff8801d7294028
Call Trace:
 [<0000000051131a67>] __dump_stack lib/dump_stack.c:15 [inline]
 [<0000000051131a67>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<000000005b838271>] print_address_description+0x6f/0x23a mm/kasan/report.c:256
 [<0000000035296d64>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<0000000035296d64>] kasan_report mm/kasan/report.c:413 [inline]
 [<0000000035296d64>] kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:397
 [<00000000722fcf27>] __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:433
 [<00000000167f3429>] tcp_connect+0x26c2/0x30b0 net/ipv4/tcp_output.c:3417
 [<00000000595ea83f>] tcp_v4_connect+0x1489/0x1c30 net/ipv4/tcp_ipv4.c:250
 [<000000006ae75a5c>] __inet_stream_connect+0x706/0xbf0 net/ipv4/af_inet.c:623
 [<00000000ab5f48e1>] inet_stream_connect+0x55/0xa0 net/ipv4/af_inet.c:687
 [<00000000a0ff5cad>] SYSC_connect net/socket.c:1576 [inline]
 [<00000000a0ff5cad>] SyS_connect+0x1a5/0x2e0 net/socket.c:1557
 [<00000000168f7815>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288
 [<00000000f9a5fc88>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Allocated by task 1997:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack mm/kasan/kasan.c:512 [inline]
 set_track mm/kasan/kasan.c:524 [inline]
 kasan_kmalloc.part.0+0x62/0xf0 mm/kasan/kasan.c:616
 kasan_kmalloc+0xb7/0xd0 mm/kasan/kasan.c:601
 kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:554
 slab_post_alloc_hook mm/slab.h:417 [inline]
 slab_alloc_node mm/slub.c:2715 [inline]
 slab_alloc mm/slub.c:2723 [inline]
 kmem_cache_alloc+0xd5/0x2b0 mm/slub.c:2728
 kmem_cache_alloc_node include/linux/slab.h:364 [inline]
 __alloc_skb+0xe7/0x5e0 net/core/skbuff.c:219
 alloc_skb_fclone include/linux/skbuff.h:966 [inline]
 sk_stream_alloc_skb+0xa3/0x5d0 net/ipv4/tcp.c:828
 tcp_sendmsg+0xe8d/0x2f90 net/ipv4/tcp.c:1230
 inet_sendmsg+0x202/0x4d0 net/ipv4/af_inet.c:766
 sock_sendmsg_nosec net/socket.c:649 [inline]
 sock_sendmsg+0xbe/0x110 net/socket.c:659
 sock_write_iter+0x235/0x3d0 net/socket.c:857
 new_sync_write fs/read_write.c:498 [inline]
 __vfs_write+0x3c1/0x560 fs/read_write.c:511
 vfs_write+0x185/0x520 fs/read_write.c:559
 SYSC_write fs/read_write.c:607 [inline]
 SyS_write+0x121/0x270 fs/read_write.c:599
 do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288
 entry_SYSCALL_64_after_swapgs+0x5d/0xdb

Freed by task 1999:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57
 save_stack mm/kasan/kasan.c:512 [inline]
 set_track mm/kasan/kasan.c:524 [inline]
 kasan_slab_free+0xb0/0x190 mm/kasan/kasan.c:589
 slab_free_hook mm/slub.c:1355 [inline]
 slab_free_freelist_hook mm/slub.c:1377 [inline]
 slab_free mm/slub.c:2958 [inline]
 kmem_cache_free+0xbe/0x310 mm/slub.c:2980
 kfree_skbmem+0x82/0x100 net/core/skbuff.c:648
 __kfree_skb+0x1e/0x30 net/core/skbuff.c:689
 sk_wmem_free_skb include/net/sock.h:1368 [inline]
 tcp_write_queue_purge include/net/tcp.h:1530 [inline]
 tcp_connect_init net/ipv4/tcp_output.c:3257 [inline]
 tcp_connect+0xa9b/0x30b0 net/ipv4/tcp_output.c:3388
 tcp_v4_connect+0x1489/0x1c30 net/ipv4/tcp_ipv4.c:250
 __inet_stream_connect+0x706/0xbf0 net/ipv4/af_inet.c:623
 inet_stream_connect+0x55/0xa0 net/ipv4/af_inet.c:687
 SYSC_connect net/socket.c:1576 [inline]
 SyS_connect+0x1a5/0x2e0 net/socket.c:1557
 do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288
 entry_SYSCALL_64_after_swapgs+0x5d/0xdb

The buggy address belongs to the object at ffff8801d7294000
 which belongs to the cache skbuff_fclone_cache of size 456
The buggy address is located 40 bytes inside of
 456-byte region [ffff8801d7294000, ffff8801d72941c8)
The buggy address belongs to the page:
page:ffffea00075ca500 count:1 mapcount:0 mapping:          (null) index:0x0 compound_mapcount: 0
flags: 0x4000000000010200(slab|head)
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d7293f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801d7293f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801d7294000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff8801d7294080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801d7294100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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