==================================================================
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 ffff8800b56747b0 by task syz-executor3/10940

CPU: 0 PID: 10940 Comm: syz-executor3 Not tainted 4.4.163+ #11
 0000000000000000 5037c6fe49294adf ffff8800b81ff7f8 ffffffff81aa556d
 ffffea0002d59d00 ffff8800b56747b0 0000000000000000 ffff8800b56747b0
 dffffc0000000000 ffff8800b81ff830 ffffffff8148a8db ffff8800b56747b0
Call Trace:
 [<ffffffff81aa556d>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81aa556d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51
 [<ffffffff8148a8db>] print_address_description+0x6c/0x217 mm/kasan/report.c:252
 [<ffffffff8148abfb>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff8148abfb>] kasan_report.cold.6+0x175/0x2f7 mm/kasan/report.c:408
 [<ffffffff8147f8e4>] __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:427
 [<ffffffff82430342>] tcp_skb_pcount include/net/tcp.h:798 [inline]
 [<ffffffff82430342>] tcp_init_tso_segs net/ipv4/tcp_output.c:1631 [inline]
 [<ffffffff82430342>] tcp_write_xmit+0x3b22/0x4680 net/ipv4/tcp_output.c:2068
 [<ffffffff82431734>] __tcp_push_pending_frames+0xa4/0x2a0 net/ipv4/tcp_output.c:2319
 [<ffffffff823e72b2>] tcp_push+0x3e2/0x5a0 net/ipv4/tcp.c:692
 [<ffffffff823f5d44>] tcp_sendmsg+0x16b4/0x2b30 net/ipv4/tcp.c:1293
 [<ffffffff824a27c3>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff821cf9eb>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff821cf9eb>] sock_sendmsg+0xbb/0x110 net/socket.c:648
 [<ffffffff821d3c10>] SYSC_sendto net/socket.c:1678 [inline]
 [<ffffffff821d3c10>] 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
 [<ffffffff82713b50>] sysenter_flags_fixed+0xd/0x1a

Allocated by task 10940:
 [<ffffffff8102e4d6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff8147e962>] save_stack mm/kasan/kasan.c:512 [inline]
 [<ffffffff8147e962>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff8147e962>] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:616
 [<ffffffff8147ebdf>] kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:601
 [<ffffffff8147f1a2>] kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:554
 [<ffffffff8147a89c>] slab_post_alloc_hook mm/slub.c:1349 [inline]
 [<ffffffff8147a89c>] slab_alloc_node mm/slub.c:2615 [inline]
 [<ffffffff8147a89c>] slab_alloc mm/slub.c:2623 [inline]
 [<ffffffff8147a89c>] kmem_cache_alloc+0xdc/0x2c0 mm/slub.c:2628
 [<ffffffff821eef56>] kmem_cache_alloc_node include/linux/slab.h:350 [inline]
 [<ffffffff821eef56>] __alloc_skb+0xe6/0x5b0 net/core/skbuff.c:218
 [<ffffffff823f2983>] alloc_skb_fclone include/linux/skbuff.h:856 [inline]
 [<ffffffff823f2983>] sk_stream_alloc_skb+0xa3/0x5d0 net/ipv4/tcp.c:833
 [<ffffffff823f5611>] tcp_sendmsg+0xf81/0x2b30 net/ipv4/tcp.c:1178
 [<ffffffff824a27c3>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff821cf9eb>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff821cf9eb>] sock_sendmsg+0xbb/0x110 net/socket.c:648
 [<ffffffff821d3c10>] SYSC_sendto net/socket.c:1678 [inline]
 [<ffffffff821d3c10>] 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
 [<ffffffff82713b50>] sysenter_flags_fixed+0xd/0x1a

Freed by task 10961:
 [<ffffffff8102e4d6>] save_stack_trace+0x26/0x50 arch/x86/kernel/stacktrace.c:63
 [<ffffffff8147f25c>] save_stack mm/kasan/kasan.c:512 [inline]
 [<ffffffff8147f25c>] set_track mm/kasan/kasan.c:524 [inline]
 [<ffffffff8147f25c>] kasan_slab_free+0xac/0x190 mm/kasan/kasan.c:589
 [<ffffffff8147bf5e>] slab_free_hook mm/slub.c:1383 [inline]
 [<ffffffff8147bf5e>] slab_free_freelist_hook mm/slub.c:1405 [inline]
 [<ffffffff8147bf5e>] slab_free mm/slub.c:2859 [inline]
 [<ffffffff8147bf5e>] kmem_cache_free+0xbe/0x350 mm/slub.c:2881
 [<ffffffff821e741f>] kfree_skbmem+0xcf/0x100 net/core/skbuff.c:635
 [<ffffffff821f47bd>] __kfree_skb+0x1d/0x20 net/core/skbuff.c:676
 [<ffffffff824324f9>] sk_wmem_free_skb include/net/sock.h:1447 [inline]
 [<ffffffff824324f9>] tcp_write_queue_purge include/net/tcp.h:1460 [inline]
 [<ffffffff824324f9>] tcp_connect_init net/ipv4/tcp_output.c:3134 [inline]
 [<ffffffff824324f9>] tcp_connect+0xae9/0x3110 net/ipv4/tcp_output.c:3273
 [<ffffffff82440401>] tcp_v4_connect+0xf31/0x1890 net/ipv4/tcp_ipv4.c:246
 [<ffffffff824a16d9>] __inet_stream_connect+0x2a9/0xc30 net/ipv4/af_inet.c:615
 [<ffffffff823f6097>] tcp_sendmsg_fastopen net/ipv4/tcp.c:1092 [inline]
 [<ffffffff823f6097>] tcp_sendmsg+0x1a07/0x2b30 net/ipv4/tcp.c:1112
 [<ffffffff824a27c3>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755
 [<ffffffff821cf9eb>] sock_sendmsg_nosec net/socket.c:638 [inline]
 [<ffffffff821cf9eb>] sock_sendmsg+0xbb/0x110 net/socket.c:648
 [<ffffffff821d3c10>] SYSC_sendto net/socket.c:1678 [inline]
 [<ffffffff821d3c10>] 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
 [<ffffffff82713b50>] sysenter_flags_fixed+0xd/0x1a

The buggy address belongs to the object at ffff8800b5674780
 which belongs to the cache skbuff_fclone_cache of size 456
The buggy address is located 48 bytes inside of
 456-byte region [ffff8800b5674780, ffff8800b5674948)
The buggy address belongs to the page:
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.4.163+ #11
task: ffff8801da6897c0 task.stack: ffff8801da698000
RIP: 0010:[<ffffffff81ab5782>]  [<ffffffff81ab5782>] __rb_insert lib/rbtree.c:120 [inline]
RIP: 0010:[<ffffffff81ab5782>]  [<ffffffff81ab5782>] rb_insert_color+0xa2/0xb60 lib/rbtree.c:420
RSP: 0018:ffff8801db707cd8  EFLAGS: 00010003
RAX: 0a0508a8e82a0be9 RBX: ffff8800b5d47b00 RCX: ffffffff828912a0
RDX: 1ffffffff0512255 RSI: ffff8801db719390 RDI: ffff8801db7198c0
RBP: ffff8801db707d18 R08: ffff8801da68a088 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000001 R12: ffffffff828912a0
R13: ffff8801db7198c0 R14: 5028454741505f4e R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000f574affc CR3: 00000001d445c000 CR4: 00000000001606b0
Stack:
 ffffffff81b035fb ffff8801db707d20 ffff8801da68a080 ffff8801db7198c0
 dffffc0000000000 0000000000000000 ffff8801db719390 ffff8800b5d47b08
 ffff8801db707d68 ffffffff81ac2bc7 ffff8801db7198d8 ffff8801db719390
Call Trace:
 <IRQ> 
 [<ffffffff81ac2bc7>] timerqueue_add+0x157/0x2b0 lib/timerqueue.c:57
 [<ffffffff8125be1f>] enqueue_hrtimer+0x15f/0x440 kernel/time/hrtimer.c:893
 [<ffffffff8125d4f4>] __run_hrtimer kernel/time/hrtimer.c:1276 [inline]
 [<ffffffff8125d4f4>] __hrtimer_run_queues+0x694/0xfc0 kernel/time/hrtimer.c:1325
 [<ffffffff8125fe71>] hrtimer_interrupt+0x1b1/0x430 kernel/time/hrtimer.c:1359
 [<ffffffff8108b594>] local_apic_timer_interrupt+0x74/0xa0 arch/x86/kernel/apic/apic.c:901
 [<ffffffff82714a3c>] smp_apic_timer_interrupt+0x7c/0xb0 arch/x86/kernel/apic/apic.c:925
 [<ffffffff82713d9d>] apic_timer_interrupt+0x9d/0xb0 arch/x86/entry/entry_64.S:741
 <EOI> 
 [<ffffffff81020cd5>] arch_safe_halt arch/x86/include/asm/paravirt.h:117 [inline]
 [<ffffffff81020cd5>] default_idle+0x55/0x3c0 arch/x86/kernel/process.c:432
 [<ffffffff81022f00>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:423
 [<ffffffff811e7be7>] default_idle_call+0x57/0x70 kernel/sched/idle.c:93
 [<ffffffff811e7ffa>] cpuidle_idle_call kernel/sched/idle.c:157 [inline]
 [<ffffffff811e7ffa>] cpu_idle_loop kernel/sched/idle.c:253 [inline]
 [<ffffffff811e7ffa>] cpu_startup_entry+0x31a/0x7a0 kernel/sched/idle.c:301
 [<ffffffff81087ec9>] start_secondary+0x329/0x400 arch/x86/kernel/smpboot.c:245
Code: 89 c2 48 c1 ea 03 42 80 3c 3a 00 0f 85 38 06 00 00 4d 8b 74 24 08 49 39 de 0f 84 6a 01 00 00 4d 85 f6 74 1c 4c 89 f0 48 c1 e8 03 <42> 80 3c 38 00 0f 85 5f 06 00 00 41 f6 06 01 0f 84 ca 02 00 00 
RIP  [<ffffffff81ab5782>] __rb_insert lib/rbtree.c:120 [inline]
RIP  [<ffffffff81ab5782>] rb_insert_color+0xa2/0xb60 lib/rbtree.c:420
 RSP <ffff8801db707cd8>
---[ end trace a4ddf2b15174b3e3 ]---