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BUG: KASAN: slab-out-of-bounds in ip6_dst_idev include/net/ip6_fib.h:192 [inline]
BUG: KASAN: slab-out-of-bounds in ip6_xmit+0x1ce9/0x2090 net/ipv6/ip6_output.c:264
Read of size 8 at addr ffff8801d6730518 by task syzkaller135211/3672

CPU: 1 PID: 3672 Comm: syzkaller135211 Not tainted 4.15.0-rc7-mm1+ #56
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_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 ip6_dst_idev include/net/ip6_fib.h:192 [inline]
 ip6_xmit+0x1ce9/0x2090 net/ipv6/ip6_output.c:264
 inet6_csk_xmit+0x2fc/0x580 net/ipv6/inet6_connection_sock.c:139
 tcp_transmit_skb+0x1b1b/0x38c0 net/ipv4/tcp_output.c:1176
 tcp_send_syn_data net/ipv4/tcp_output.c:3457 [inline]
 tcp_connect+0x1edb/0x4090 net/ipv4/tcp_output.c:3496
 tcp_v4_connect+0x15ef/0x1e70 net/ipv4/tcp_ipv4.c:257
 __inet_stream_connect+0x2d4/0xf00 net/ipv4/af_inet.c:620
 tcp_sendmsg_fastopen net/ipv4/tcp.c:1168 [inline]
 tcp_sendmsg_locked+0x264e/0x3c70 net/ipv4/tcp.c:1214
 tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1463
 inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:764
 sock_sendmsg_nosec net/socket.c:630 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:640
 ___sys_sendmsg+0x320/0x8b0 net/socket.c:2020
 __sys_sendmmsg+0x1ee/0x620 net/socket.c:2110
 SYSC_sendmmsg net/socket.c:2141 [inline]
 SyS_sendmmsg+0x35/0x60 net/socket.c:2136
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x43fdd9
RSP: 002b:00007ffc241f4328 EFLAGS: 00000217 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fdd9
RDX: 0000000000000001 RSI: 00000000205f8fc8 RDI: 0000000000000004
RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000020000000 R11: 0000000000000217 R12: 0000000000401740
R13: 00000000004017d0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 0:
(stack is not available)

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8801d6730500
 which belongs to the cache ip_dst_cache of size 168
The buggy address is located 24 bytes inside of
 168-byte region [ffff8801d6730500, ffff8801d67305a8)
The buggy address belongs to the page:
page:ffffea000759cc00 count:1 mapcount:0 mapping:ffff8801d6730000 index:0xffff8801d6730000
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801d6730000 ffff8801d6730000 000000010000000d
raw: ffff8801d6f67a38 ffff8801d6f67a38 ffff8801d6f68980 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d6730400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801d6730480: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
>ffff8801d6730500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                            ^
 ffff8801d6730580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801d6730600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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