syzbot

8021q: adding VLAN 0 to HW filter on device bond0
IPv6: ADDRCONF(NETDEV_UP): veth0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
audit: type=1400 audit(1521114582.482:10): avc:  denied  { sys_chroot } for  pid=4233 comm="syzkaller448085" capability=18  scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns permissive=1
==================================================================
BUG: KASAN: use-after-free in ip6_dst_idev include/net/ip6_fib.h:192 [inline]
BUG: KASAN: use-after-free in ip6_xmit+0x1f76/0x2260 net/ipv6/ip6_output.c:264
Read of size 8 at addr ffff8801a998d818 by task syzkaller448085/4233

CPU: 1 PID: 4233 Comm: syzkaller448085 Not tainted 4.16.0-rc5+ #354
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+0x194/0x24d 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+0x23c/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+0x1f76/0x2260 net/ipv6/ip6_output.c:264
 inet6_csk_xmit+0x2fc/0x580 net/ipv6/inet6_connection_sock.c:139
 l2tp_xmit_core net/l2tp/l2tp_core.c:1053 [inline]
 l2tp_xmit_skb+0x105f/0x1410 net/l2tp/l2tp_core.c:1148
 pppol2tp_sendmsg+0x470/0x670 net/l2tp/l2tp_ppp.c:341
 sock_sendmsg_nosec net/socket.c:630 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:640
 ___sys_sendmsg+0x767/0x8b0 net/socket.c:2046
 __sys_sendmsg+0xe5/0x210 net/socket.c:2080
 SYSC_sendmsg net/socket.c:2091 [inline]
 SyS_sendmsg+0x2d/0x50 net/socket.c:2087
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x441c59
RSP: 002b:00000000007dfea8 EFLAGS: 00000217 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000000001a RCX: 0000000000441c59
RDX: 0000000000000081 RSI: 000000002037ffc8 RDI: 0000000000000004
RBP: 00000000004a3c86 R08: 0000000120080522 R09: 0000000120080522
R10: 0000000120080522 R11: 0000000000000217 R12: 00000000007dff70
R13: 0000000000402c90 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 4230:
 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
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3541
 dst_alloc+0x11f/0x1a0 net/core/dst.c:104
 rt_dst_alloc+0xe9/0x520 net/ipv4/route.c:1507
 __mkroute_output net/ipv4/route.c:2251 [inline]
 ip_route_output_key_hash_rcu+0xa59/0x2f00 net/ipv4/route.c:2479
 ip_route_output_key_hash+0x20b/0x370 net/ipv4/route.c:2308
 __ip_route_output_key include/net/route.h:125 [inline]
 ip_route_connect include/net/route.h:300 [inline]
 __ip4_datagram_connect+0xa67/0x1240 net/ipv4/datagram.c:51
 __ip6_datagram_connect+0x749/0x12d0 net/ipv6/datagram.c:157
 ip6_datagram_connect+0x2f/0x50 net/ipv6/datagram.c:273
 inet_dgram_connect+0x16b/0x1f0 net/ipv4/af_inet.c:542
 SYSC_connect+0x213/0x4a0 net/socket.c:1639
 SyS_connect+0x24/0x30 net/socket.c:1620
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 0:
 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]
 kmem_cache_free+0x83/0x2a0 mm/slab.c:3743
 dst_destroy+0x257/0x370 net/core/dst.c:140
 dst_destroy_rcu+0x16/0x20 net/core/dst.c:153
 __rcu_reclaim kernel/rcu/rcu.h:172 [inline]
 rcu_do_batch kernel/rcu/tree.c:2674 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2933 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2900 [inline]
 rcu_process_callbacks+0xd6c/0x17f0 kernel/rcu/tree.c:2917
 __do_softirq+0x2d7/0xb85 kernel/softirq.c:285

The buggy address belongs to the object at ffff8801a998d800
 which belongs to the cache ip_dst_cache of size 168
The buggy address is located 24 bytes inside of
 168-byte region [ffff8801a998d800, ffff8801a998d8a8)
The buggy address belongs to the page:
page:ffffea0006a66340 count:1 mapcount:0 mapping:ffff8801a998d000 index:0xffff8801a998d000
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801a998d000 ffff8801a998d000 0000000100000009
raw: ffff8801d588c638 ffffea0006c37060 ffff8801d5bae800 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801a998d700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801a998d780: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
>ffff8801a998d800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff8801a998d880: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
 ffff8801a998d900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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