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BUG: KASAN: slab-out-of-bounds in ip6_dst_idev include/net/ip6_fib.h:141 [inline]
BUG: KASAN: slab-out-of-bounds in ip6_xmit+0x1838/0x1b80 net/ipv6/ip6_output.c:254
Read of size 8 at addr ffff8801d80e2b58 by task syz-executor0/6993

CPU: 1 PID: 6993 Comm: syz-executor0 Not tainted 4.9.124-g09eb2ba #35
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801cc28f530 ffffffff81eb95e9 ffffea0007603880 ffff8801d80e2b58
 0000000000000000 ffff8801d80e2b58 0000000000000040 ffff8801cc28f568
 ffffffff8156c35e ffff8801d80e2b58 0000000000000008 0000000000000000
Call Trace:
 [<ffffffff81eb95e9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81eb95e9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8156c35e>] print_address_description+0x6c/0x234 mm/kasan/report.c:256
 [<ffffffff8156c768>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff8156c768>] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412
 [<ffffffff8153faf4>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 [<ffffffff83562358>] ip6_dst_idev include/net/ip6_fib.h:141 [inline]
 [<ffffffff83562358>] ip6_xmit+0x1838/0x1b80 net/ipv6/ip6_output.c:254
 [<ffffffff836275ec>] inet6_csk_xmit+0x27c/0x4d0 net/ipv6/inet6_connection_sock.c:178
 [<ffffffff836c42e5>] l2tp_xmit_core net/l2tp/l2tp_core.c:1178 [inline]
 [<ffffffff836c42e5>] l2tp_xmit_skb+0xc45/0xf30 net/l2tp/l2tp_core.c:1273
 [<ffffffff836cf8b0>] pppol2tp_sendmsg+0x4e0/0x790 net/l2tp/l2tp_ppp.c:339
 [<ffffffff8301e0ac>] sock_sendmsg_nosec net/socket.c:648 [inline]
 [<ffffffff8301e0ac>] sock_sendmsg+0xcc/0x110 net/socket.c:658
 [<ffffffff8301f8ca>] ___sys_sendmsg+0x47a/0x840 net/socket.c:1982
 [<ffffffff83021f0c>] __sys_sendmmsg+0x23c/0x3d0 net/socket.c:2065
 [<ffffffff83123802>] C_SYSC_sendmmsg net/compat.c:742 [inline]
 [<ffffffff83123802>] compat_SyS_sendmmsg+0x32/0x40 net/compat.c:739
 [<ffffffff81006da7>] do_syscall_32_irqs_on arch/x86/entry/common.c:325 [inline]
 [<ffffffff81006da7>] do_fast_syscall_32+0x2f7/0x870 arch/x86/entry/common.c:387
 [<ffffffff83a030d0>] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137

Allocated by task 0:
(stack is not available)

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8801d80e2b40
 which belongs to the cache ip_dst_cache of size 216
The buggy address is located 24 bytes inside of
 216-byte region [ffff8801d80e2b40, ffff8801d80e2c18)
The buggy address belongs to the page:
page:ffffea0007603880 count:1 mapcount:0 mapping:          (null) index:0x0
flags: 0x8000000000000080(slab)
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d80e2a00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801d80e2a80: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
>ffff8801d80e2b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                    ^
 ffff8801d80e2b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801d80e2c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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