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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 ffff8801a9995018 by task syz-executor6/28123

CPU: 0 PID: 28123 Comm: syz-executor6 Not tainted 4.16.0-rc4+ #260
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:629 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:639
 ___sys_sendmsg+0x767/0x8b0 net/socket.c:2047
 __sys_sendmsg+0xe5/0x210 net/socket.c:2081
 SYSC_sendmsg net/socket.c:2092 [inline]
 SyS_sendmsg+0x2d/0x50 net/socket.c:2088
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x453e69
RSP: 002b:00007f3584dfbc68 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f3584dfc6d4 RCX: 0000000000453e69
RDX: 0000000000000081 RSI: 000000002037ffc8 RDI: 0000000000000015
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000004c3 R14: 00000000006f72e8 R15: 0000000000000000

Allocated by task 24604:
 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
 kmem_cache_alloc_trace+0x136/0x740 mm/slab.c:3607
 kmalloc include/linux/slab.h:512 [inline]
 kzalloc include/linux/slab.h:701 [inline]
 sctp_add_bind_addr+0xd8/0x460 net/sctp/bind_addr.c:159
 sctp_copy_local_addr_list+0x4bb/0x5e0 net/sctp/protocol.c:230
 sctp_copy_one_addr+0xdc/0x120 net/sctp/bind_addr.c:449
 sctp_bind_addr_copy+0x167/0x360 net/sctp/bind_addr.c:71
 sctp_assoc_set_bind_addr_from_ep+0x136/0x190 net/sctp/associola.c:1578
 __sctp_connect+0x61d/0xca0 net/sctp/socket.c:1205
 sctp_connect+0xb4/0xf0 net/sctp/socket.c:4315
 inet_dgram_connect+0x16b/0x1f0 net/ipv4/af_inet.c:542
 SYSC_connect+0x213/0x4a0 net/socket.c:1640
 SyS_connect+0x24/0x30 net/socket.c:1621
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 4244:
 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
 __rcu_reclaim kernel/rcu/rcu.h:167 [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+0xe94/0x17f0 kernel/rcu/tree.c:2917
 __do_softirq+0x2d7/0xb85 kernel/softirq.c:285

The buggy address belongs to the object at ffff8801a9995000
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 24 bytes inside of
 64-byte region [ffff8801a9995000, ffff8801a9995040)
The buggy address belongs to the page:
page:ffffea0006a66540 count:1 mapcount:0 mapping:ffff8801a9995000 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801a9995000 0000000000000000 0000000100000020
raw: ffffea0006cb1260 ffffea0006d210e0 ffff8801dac00340 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801a9994f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801a9994f80: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801a9995000: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                            ^
 ffff8801a9995080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801a9995100: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
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