audit: type=1400 audit(1569004602.049:36): avc:  denied  { map } for  pid=6968 comm="syz-executor629" path="/root/syz-executor629693129" dev="sda1" ino=16482 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_t:s0 tclass=file permissive=1
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
==================================================================
BUG: KASAN: use-after-free in tcp_skb_pcount include/net/tcp.h:911 [inline]
BUG: KASAN: use-after-free in tcp_init_tso_segs+0x1ae/0x200 net/ipv4/tcp_output.c:1790
Read of size 2 at addr ffff88809fa25af0 by task syz-executor629/6968

CPU: 0 PID: 6968 Comm: syz-executor629 Not tainted 4.14.145 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x138/0x197 lib/dump_stack.c:53
 print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2af mm/kasan/report.c:393
 __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:428
 tcp_skb_pcount include/net/tcp.h:911 [inline]
 tcp_init_tso_segs+0x1ae/0x200 net/ipv4/tcp_output.c:1790
 tcp_write_xmit+0x15e/0x4960 net/ipv4/tcp_output.c:2330
 __tcp_push_pending_frames+0xa6/0x260 net/ipv4/tcp_output.c:2563
 tcp_send_fin+0x17e/0xc40 net/ipv4/tcp_output.c:3115
 tcp_close+0xcc8/0xfb0 net/ipv4/tcp.c:2221
 inet_release+0xec/0x1c0 net/ipv4/af_inet.c:425
 inet6_release+0x53/0x80 net/ipv6/af_inet6.c:450
 __sock_release+0xce/0x2b0 net/socket.c:602
 sock_close+0x1b/0x30 net/socket.c:1139
 __fput+0x275/0x7a0 fs/file_table.c:210
 ____fput+0x16/0x20 fs/file_table.c:244
 task_work_run+0x114/0x190 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x7df/0x2c10 kernel/exit.c:874
 do_group_exit+0x111/0x330 kernel/exit.c:977
 SYSC_exit_group kernel/exit.c:988 [inline]
 SyS_exit_group+0x1d/0x20 kernel/exit.c:986
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x43ee88
RSP: 002b:00007fff9a655f08 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043ee88
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000004be688 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 0000000020000001 R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006d0180 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 6968:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529
 kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc_node+0x144/0x780 mm/slab.c:3642
 __alloc_skb+0x9c/0x500 net/core/skbuff.c:193
 alloc_skb_fclone include/linux/skbuff.h:1022 [inline]
 sk_stream_alloc_skb+0xb3/0x780 net/ipv4/tcp.c:855
 tcp_sendmsg_locked+0xf61/0x3200 net/ipv4/tcp.c:1301
 tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1457
 inet_sendmsg+0x122/0x500 net/ipv4/af_inet.c:762
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xce/0x110 net/socket.c:656
 SYSC_sendto+0x206/0x310 net/socket.c:1763
 SyS_sendto+0x40/0x50 net/socket.c:1731
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 6968:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kmem_cache_free+0x83/0x2b0 mm/slab.c:3758
 kfree_skbmem+0x8d/0x120 net/core/skbuff.c:607
 __kfree_skb+0x1e/0x30 net/core/skbuff.c:646
 sk_wmem_free_skb include/net/sock.h:1416 [inline]
 tcp_remove_empty_skb.part.0+0x231/0x2e0 net/ipv4/tcp.c:929
 tcp_remove_empty_skb net/ipv4/tcp.c:925 [inline]
 tcp_sendmsg_locked+0x1ced/0x3200 net/ipv4/tcp.c:1435
 tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1457
 inet_sendmsg+0x122/0x500 net/ipv4/af_inet.c:762
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xce/0x110 net/socket.c:656
 SYSC_sendto+0x206/0x310 net/socket.c:1763
 SyS_sendto+0x40/0x50 net/socket.c:1731
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff88809fa25ac0
 which belongs to the cache skbuff_fclone_cache of size 472
The buggy address is located 48 bytes inside of
 472-byte region [ffff88809fa25ac0, ffff88809fa25c98)
The buggy address belongs to the page:
page:ffffea00027e8940 count:1 mapcount:0 mapping:ffff88809fa250c0 index:0x0
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffff88809fa250c0 0000000000000000 0000000100000006
raw: ffffea00025b98e0 ffffea00020e1060 ffff8880a9e81d80 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809fa25980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809fa25a00: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88809fa25a80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                                             ^
 ffff88809fa25b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809fa25b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================