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BUG: KASAN: use-after-free in tcp_skb_pcount include/net/tcp.h:912 [inline]
BUG: KASAN: use-after-free in tcp_init_tso_segs+0x19d/0x1f0 net/ipv4/tcp_output.c:1790
Read of size 2 at addr ffff8881b8ab7430 by task ksoftirqd/0/7

CPU: 0 PID: 7 Comm: ksoftirqd/0 Not tainted 4.14.143+ #0
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xca/0x134 lib/dump_stack.c:53
 print_address_description+0x60/0x226 mm/kasan/report.c:187
 __kasan_report.cold+0x1a/0x41 mm/kasan/report.c:316
 tcp_skb_pcount include/net/tcp.h:912 [inline]
 tcp_init_tso_segs+0x19d/0x1f0 net/ipv4/tcp_output.c:1790
 tcp_write_xmit+0x15a/0x4730 net/ipv4/tcp_output.c:2330
 __tcp_push_pending_frames+0xa0/0x230 net/ipv4/tcp_output.c:2563
 tcp_push_pending_frames include/net/tcp.h:1771 [inline]
 tcp_data_snd_check net/ipv4/tcp_input.c:5120 [inline]
 tcp_rcv_established+0x648/0x1610 net/ipv4/tcp_input.c:5567
 tcp_v4_do_rcv+0x568/0x700 net/ipv4/tcp_ipv4.c:1467
 tcp_v4_rcv+0x23e9/0x3230 net/ipv4/tcp_ipv4.c:1741
 ip_local_deliver_finish+0x3a3/0xa30 net/ipv4/ip_input.c:216
 NF_HOOK include/linux/netfilter.h:250 [inline]
 ip_local_deliver+0x373/0x450 net/ipv4/ip_input.c:257
 dst_input include/net/dst.h:468 [inline]
 ip_rcv_finish+0x4ed/0x1610 net/ipv4/ip_input.c:396
 NF_HOOK include/linux/netfilter.h:250 [inline]
 ip_rcv+0xa30/0xf55 net/ipv4/ip_input.c:493
 __netif_receive_skb_core+0x13ad/0x2cf0 net/core/dev.c:4477
 __netif_receive_skb+0x66/0x210 net/core/dev.c:4515
 process_backlog+0x1dc/0x640 net/core/dev.c:5197
 napi_poll net/core/dev.c:5598 [inline]
 net_rx_action+0x366/0xcd0 net/core/dev.c:5664
 __do_softirq+0x234/0x9ec kernel/softirq.c:288
 run_ksoftirqd+0x2d/0xe0 kernel/softirq.c:670
 smpboot_thread_fn+0x5df/0x920 kernel/smpboot.c:164
 kthread+0x31f/0x430 kernel/kthread.c:232
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:404

Allocated by task 6378:
 save_stack mm/kasan/common.c:76 [inline]
 set_track mm/kasan/common.c:85 [inline]
 __kasan_kmalloc.part.0+0x53/0xc0 mm/kasan/common.c:495
 slab_post_alloc_hook mm/slab.h:439 [inline]
 slab_alloc_node mm/slub.c:2792 [inline]
 slab_alloc mm/slub.c:2800 [inline]
 kmem_cache_alloc+0xee/0x360 mm/slub.c:2805
 kmem_cache_alloc_node include/linux/slab.h:361 [inline]
 __alloc_skb+0xea/0x5c0 net/core/skbuff.c:193
 alloc_skb_fclone include/linux/skbuff.h:1022 [inline]
 sk_stream_alloc_skb+0xf4/0x8a0 net/ipv4/tcp.c:855
 tcp_sendmsg_locked+0xf11/0x2f50 net/ipv4/tcp.c:1301
 tcp_sendmsg+0x2b/0x40 net/ipv4/tcp.c:1457
 inet_sendmsg+0x15b/0x520 net/ipv4/af_inet.c:760
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb7/0x100 net/socket.c:656
 ___sys_sendmsg+0x368/0x890 net/socket.c:2062
 __sys_sendmmsg+0x13c/0x360 net/socket.c:2152
 SYSC_sendmmsg net/socket.c:2183 [inline]
 SyS_sendmmsg+0x2f/0x50 net/socket.c:2178
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
 0xffffffffffffffff

Freed by task 6378:
 save_stack mm/kasan/common.c:76 [inline]
 set_track mm/kasan/common.c:85 [inline]
 __kasan_slab_free+0x164/0x210 mm/kasan/common.c:457
 slab_free_hook mm/slub.c:1407 [inline]
 slab_free_freelist_hook mm/slub.c:1458 [inline]
 slab_free mm/slub.c:3039 [inline]
 kmem_cache_free+0xd7/0x3b0 mm/slub.c:3055
 kfree_skbmem+0x84/0x110 net/core/skbuff.c:607
 sk_wmem_free_skb include/net/sock.h:1416 [inline]
 tcp_remove_empty_skb net/ipv4/tcp.c:929 [inline]
 tcp_remove_empty_skb+0x264/0x320 net/ipv4/tcp.c:923
 tcp_sendmsg_locked+0x1c09/0x2f50 net/ipv4/tcp.c:1435
 tcp_sendmsg+0x2b/0x40 net/ipv4/tcp.c:1457
 inet_sendmsg+0x15b/0x520 net/ipv4/af_inet.c:760
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb7/0x100 net/socket.c:656
 ___sys_sendmsg+0x368/0x890 net/socket.c:2062
 __sys_sendmmsg+0x13c/0x360 net/socket.c:2152
 SYSC_sendmmsg net/socket.c:2183 [inline]
 SyS_sendmmsg+0x2f/0x50 net/socket.c:2178
 do_syscall_64+0x19b/0x520 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
 0xffffffffffffffff

The buggy address belongs to the object at ffff8881b8ab7400
 which belongs to the cache skbuff_fclone_cache of size 456
The buggy address is located 48 bytes inside of
 456-byte region [ffff8881b8ab7400, ffff8881b8ab75c8)
The buggy address belongs to the page:
page:ffffea0006e2ad80 count:1 mapcount:0 mapping:          (null) index:0x0 compound_mapcount: 0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 0000000000000000 0000000000000000 00000001800c000c
raw: dead000000000100 dead000000000200 ffff8881dab70400 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8881b8ab7300: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
 ffff8881b8ab7380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881b8ab7400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff8881b8ab7480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881b8ab7500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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