==================================================================
BUG: KASAN: use-after-free in tcp_skb_pcount include/net/tcp.h:798 [inline]
BUG: KASAN: use-after-free in tcp_init_tso_segs net/ipv4/tcp_output.c:1631 [inline]
BUG: KASAN: use-after-free in tcp_write_xmit+0x3b22/0x4680 net/ipv4/tcp_output.c:2068
Read of size 2 at addr ffff8800b9169430 by task syz-executor3/4446

CPU: 0 PID: 4446 Comm: syz-executor3 Not tainted 4.4.164+ #13
 0000000000000000 f99ff9a47fc7276e ffff8801d67b7858 ffffffff81aa5d4d
 ffffea0002e45a00 ffff8800b9169430 0000000000000000 ffff8800b9169430
 dffffc0000000000 ffff8801d67b7890 ffffffff8148b2eb ffff8800b9169430
Call Trace:
 [<ffffffff81aa5d4d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81aa5d4d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff8148b2eb>] print_address_description+0x6c/0x217 mm/kasan/report.c:252
 [<ffffffff8148b60b>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff8148b60b>] kasan_report.cold.6+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff814802f4>] __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:427
 [<ffffffff82430a32>] tcp_skb_pcount include/net/tcp.h:798 [inline]
 [<ffffffff82430a32>] tcp_init_tso_segs net/ipv4/tcp_output.c:1631 [inline]
 [<ffffffff82430a32>] tcp_write_xmit+0x3b22/0x4680 net/ipv4/tcp_output.c:2068
 [<ffffffff82431e24>] __tcp_push_pending_frames+0xa4/0x2a0 net/ipv4/tcp_output.c:2319
 [<ffffffff823f6f23>] tcp_sendmsg+0x21a3/0x2b30 net/ipv4/tcp.c:1272
 [<ffffffff824a2eb3>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff821d00db>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff821d00db>] sock_sendmsg+0xbb/0x110 net/socket.c:648
 [<ffffffff821d4300>] SYSC_sendto net/socket.c:1678 [inline]
 [<ffffffff821d4300>] SyS_sendto+0x220/0x370 net/socket.c:1646
 [<ffffffff8100629e>] do_syscall_32_irqs_on arch/x86/entry/common.c:396 [inline]
 [<ffffffff8100629e>] do_fast_syscall_32+0x31e/0xa80 arch/x86/entry/common.c:463
 [<ffffffff827155d0>] sysenter_flags_fixed+0xd/0x1a

Allocated by task 4446:
 [<ffffffff8102e566>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff8147f372>] save_stack mm/kasan/kasan.c:512 [inline]
 [<ffffffff8147f372>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff8147f372>] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:616
 [<ffffffff8147f5ef>] kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:601
 [<ffffffff8147fbb2>] kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:554
 [<ffffffff8147b2ac>] slab_post_alloc_hook mm/slub.c:1349 [inline]
 [<ffffffff8147b2ac>] slab_alloc_node mm/slub.c:2615 [inline]
 [<ffffffff8147b2ac>] slab_alloc mm/slub.c:2623 [inline]
 [<ffffffff8147b2ac>] kmem_cache_alloc+0xdc/0x2c0 mm/slub.c:2628
 [<ffffffff821ef646>] kmem_cache_alloc_node include/linux/slab.h:350 [inline]
 [<ffffffff821ef646>] __alloc_skb+0xe6/0x5b0 net/core/skbuff.c:218
 [<ffffffff823f3073>] alloc_skb_fclone include/linux/skbuff.h:856 [inline]
 [<ffffffff823f3073>] sk_stream_alloc_skb+0xa3/0x5d0 net/ipv4/tcp.c:833
 [<ffffffff823f5d01>] tcp_sendmsg+0xf81/0x2b30 net/ipv4/tcp.c:1178
 [<ffffffff824a2eb3>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff821d00db>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff821d00db>] sock_sendmsg+0xbb/0x110 net/socket.c:648
 [<ffffffff821d4300>] SYSC_sendto net/socket.c:1678 [inline]
 [<ffffffff821d4300>] SyS_sendto+0x220/0x370 net/socket.c:1646
 [<ffffffff8100629e>] do_syscall_32_irqs_on arch/x86/entry/common.c:396 [inline]
 [<ffffffff8100629e>] do_fast_syscall_32+0x31e/0xa80 arch/x86/entry/common.c:463
 [<ffffffff827155d0>] sysenter_flags_fixed+0xd/0x1a

Freed by task 4460:
 [<ffffffff8102e566>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff8147fc6c>] save_stack mm/kasan/kasan.c:512 [inline]
 [<ffffffff8147fc6c>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff8147fc6c>] kasan_slab_free+0xac/0x190 mm/kasan/kasan.c:589
 [<ffffffff8147c96e>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff8147c96e>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff8147c96e>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff8147c96e>] kmem_cache_free+0xbe/0x350 mm/slub.c:2881
 [<ffffffff821e7b0f>] kfree_skbmem+0xcf/0x100 net/core/skbuff.c:635
 [<ffffffff821f4ead>] __kfree_skb+0x1d/0x20 net/core/skbuff.c:676
 [<ffffffff82432be9>] sk_wmem_free_skb include/net/sock.h:1447 [inline]
 [<ffffffff82432be9>] tcp_write_queue_purge include/net/tcp.h:1460 [inline]
 [<ffffffff82432be9>] tcp_connect_init net/ipv4/tcp_output.c:3134 [inline]
 [<ffffffff82432be9>] tcp_connect+0xae9/0x3110 net/ipv4/tcp_output.c:3273
 [<ffffffff82440af1>] tcp_v4_connect+0xf31/0x1890 net/ipv4/tcp_ipv4.c:246
 [<ffffffff824a1dc9>] __inet_stream_connect+0x2a9/0xc30 net/ipv4/af_inet.c:615
 [<ffffffff824a27a5>] inet_stream_connect+0x55/0xa0 net/ipv4/af_inet.c:676
 [<ffffffff821d3a68>] SYSC_connect net/socket.c:1570 [inline]
 [<ffffffff821d3a68>] SyS_connect+0x1b8/0x310 net/socket.c:1551
 [<ffffffff8100629e>] do_syscall_32_irqs_on arch/x86/entry/common.c:396 [inline]
 [<ffffffff8100629e>] do_fast_syscall_32+0x31e/0xa80 arch/x86/entry/common.c:463
 [<ffffffff827155d0>] sysenter_flags_fixed+0xd/0x1a

The buggy address belongs to the object at ffff8800b9169400
 which belongs to the cache skbuff_fclone_cache of size 456
The buggy address is located 48 bytes inside of
 456-byte region [ffff8800b9169400, ffff8800b91695c8)
The buggy address belongs to the page: