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BUG: KASAN: use-after-free in __tcp_hdrlen include/linux/tcp.h:35 [inline]
BUG: KASAN: use-after-free in tcp_hdrlen include/linux/tcp.h:40 [inline]
BUG: KASAN: use-after-free in qdisc_pkt_len_init net/core/dev.c:3171 [inline]
BUG: KASAN: use-after-free in __dev_queue_xmit+0x297c/0x2b50 net/core/dev.c:3477
Read of size 2 at addr ffff8801d67e52d8 by task syz-executor7/7049

CPU: 0 PID: 7049 Comm: syz-executor7 Not tainted 4.15.0-rc6-mm1+ #52
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+0x194/0x257 lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report+0x23b/0x360 mm/kasan/report.c:412
 __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:431
 __tcp_hdrlen include/linux/tcp.h:35 [inline]
 tcp_hdrlen include/linux/tcp.h:40 [inline]
 qdisc_pkt_len_init net/core/dev.c:3171 [inline]
 __dev_queue_xmit+0x297c/0x2b50 net/core/dev.c:3477
 dev_queue_xmit+0x17/0x20 net/core/dev.c:3566
 packet_snd net/packet/af_packet.c:2944 [inline]
 packet_sendmsg+0x3aed/0x60b0 net/packet/af_packet.c:2969
 sock_sendmsg_nosec net/socket.c:628 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:638
 sock_write_iter+0x31a/0x5d0 net/socket.c:907
 call_write_iter include/linux/fs.h:1775 [inline]
 new_sync_write fs/read_write.c:469 [inline]
 __vfs_write+0x684/0x970 fs/read_write.c:482
 vfs_write+0x189/0x510 fs/read_write.c:544
 SYSC_write fs/read_write.c:589 [inline]
 SyS_write+0xef/0x220 fs/read_write.c:581
 entry_SYSCALL_64_fastpath+0x23/0x9a
RIP: 0033:0x452ac9
RSP: 002b:00007f67d20a0c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452ac9
RDX: 0000000000000062 RSI: 00000000202a3f5e RDI: 0000000000000015
RBP: 000000000000034b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f2fa8
R13: 00000000ffffffff R14: 00007f67d20a16d4 R15: 0000000000000000

Allocated by task 5434:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552
 __do_kmalloc_node mm/slab.c:3669 [inline]
 __kmalloc_node_track_caller+0x47/0x70 mm/slab.c:3683
 __kmalloc_reserve.isra.39+0x41/0xd0 net/core/skbuff.c:137
 __alloc_skb+0x13b/0x780 net/core/skbuff.c:205
 alloc_skb include/linux/skbuff.h:983 [inline]
 alloc_skb_with_frags+0x10d/0x750 net/core/skbuff.c:5151
 sock_alloc_send_pskb+0x787/0x9b0 net/core/sock.c:2088
 unix_dgram_sendmsg+0x52d/0x1610 net/unix/af_unix.c:1682
 unix_seqpacket_sendmsg+0xf3/0x160 net/unix/af_unix.c:2063
 sock_sendmsg_nosec net/socket.c:628 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:638
 ___sys_sendmsg+0x320/0x8b0 net/socket.c:2018
 __sys_sendmmsg+0x1ee/0x620 net/socket.c:2108
 SYSC_sendmmsg net/socket.c:2139 [inline]
 SyS_sendmmsg+0x35/0x60 net/socket.c:2134
 entry_SYSCALL_64_fastpath+0x23/0x9a

Freed by task 5434:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
 __cache_free mm/slab.c:3485 [inline]
 kfree+0xd9/0x260 mm/slab.c:3800
 skb_free_head+0x74/0xb0 net/core/skbuff.c:550
 skb_release_data+0x58c/0x790 net/core/skbuff.c:570
 skb_release_all+0x4a/0x60 net/core/skbuff.c:627
 __kfree_skb net/core/skbuff.c:641 [inline]
 kfree_skb+0x15d/0x4c0 net/core/skbuff.c:659
 unix_dgram_sendmsg+0xcbd/0x1610 net/unix/af_unix.c:1819
 unix_seqpacket_sendmsg+0xf3/0x160 net/unix/af_unix.c:2063
 sock_sendmsg_nosec net/socket.c:628 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:638
 ___sys_sendmsg+0x320/0x8b0 net/socket.c:2018
 __sys_sendmmsg+0x1ee/0x620 net/socket.c:2108
 SYSC_sendmmsg net/socket.c:2139 [inline]
 SyS_sendmmsg+0x35/0x60 net/socket.c:2134
 entry_SYSCALL_64_fastpath+0x23/0x9a

The buggy address belongs to the object at ffff8801d67e5280
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 88 bytes inside of
 512-byte region [ffff8801d67e5280, ffff8801d67e5480)
The buggy address belongs to the page:
page:ffffea000759f940 count:1 mapcount:0 mapping:ffff8801d67e5000 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801d67e5000 0000000000000000 0000000100000006
raw: ffffea000759f920 ffffea000759f9a0 ffff8801dac00940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d67e5180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801d67e5200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801d67e5280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff8801d67e5300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801d67e5380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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