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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 ffff88809c8a92f0 by task syz-executor.0/12539

CPU: 0 PID: 12539 Comm: syz-executor.0 Not tainted 4.14.144 #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
 __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
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1da/0x220 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4bc/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x4598e9
RSP: 002b:00007f89157d2c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 00000000004598e9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f89157d36d4
R13: 00000000004f90b2 R14: 00000000004d1b90 R15: 00000000ffffffff

Allocated by task 12539:
 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 12539:
 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 ffff88809c8a92c0
 which belongs to the cache skbuff_fclone_cache of size 472
The buggy address is located 48 bytes inside of
 472-byte region [ffff88809c8a92c0, ffff88809c8a9498)
The buggy address belongs to the page:
page:ffffea0002722a40 count:1 mapcount:0 mapping:ffff88809c8a9040 index:0x0
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffff88809c8a9040 0000000000000000 0000000100000006
raw: ffffea000257eaa0 ffffea00024b36e0 ffff8880a9e82d80 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809c8a9180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809c8a9200: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88809c8a9280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                                             ^
 ffff88809c8a9300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809c8a9380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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