==================================================================
BUG: KASAN: use-after-free in __read_once_size include/linux/compiler.h:183 [inline]
BUG: KASAN: use-after-free in sk_dst_get include/net/sock.h:1766 [inline]
BUG: KASAN: use-after-free in pppol2tp_connect+0x1692/0x18b0 net/l2tp/l2tp_ppp.c:749
Read of size 8 at addr ffff8880a08539e8 by task syz-executor.4/7136

CPU: 0 PID: 7136 Comm: syz-executor.4 Not tainted 4.14.171-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
IPv6: addrconf: prefix option has invalid lifetime
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x142/0x197 lib/dump_stack.c:58
 print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2af mm/kasan/report.c:393
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 __read_once_size include/linux/compiler.h:183 [inline]
 sk_dst_get include/net/sock.h:1766 [inline]
 pppol2tp_connect+0x1692/0x18b0 net/l2tp/l2tp_ppp.c:749
 SYSC_connect+0x1f6/0x2d0 net/socket.c:1655
 SyS_connect+0x24/0x30 net/socket.c:1636
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x45c449
RSP: 002b:00007f97068a0c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f97068a16d4 RCX: 000000000045c449
RDX: 0000000000000032 RSI: 0000000020000040 RDI: 0000000000000003
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000008d R14: 00000000004c2e2e R15: 000000000076bf2c

Allocated by task 7127:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529
 kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x780 mm/slab.c:3552
 sk_prot_alloc+0x67/0x2a0 net/core/sock.c:1461
 sk_alloc+0x39/0xd70 net/core/sock.c:1521
 inet6_create net/ipv6/af_inet6.c:183 [inline]
 inet6_create+0x2d8/0xe10 net/ipv6/af_inet6.c:110
 __sock_create+0x2f6/0x620 net/socket.c:1275
 sock_create net/socket.c:1315 [inline]
 SYSC_socket net/socket.c:1345 [inline]
 SyS_socket+0xd3/0x170 net/socket.c:1325
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 7123:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kmem_cache_free+0x83/0x2b0 mm/slab.c:3758
 sk_prot_free net/core/sock.c:1502 [inline]
 __sk_destruct+0x3c5/0x650 net/core/sock.c:1581
 sk_destruct+0xa4/0xd0 net/core/sock.c:1596
 __sk_free+0x54/0x230 net/core/sock.c:1604
 sk_free+0x35/0x40 net/core/sock.c:1615
 sock_put include/net/sock.h:1658 [inline]
 sk_common_release+0x207/0x310 net/core/sock.c:3019
 udp_lib_close+0x16/0x20 include/net/udp.h:203
 inet_release+0xec/0x1c0 net/ipv4/af_inet.c:425
 inet6_release+0x53/0x80 net/ipv6/af_inet6.c:450
 __sock_release+0xce/0x2b0 net/socket.c:602
 sock_close+0x1b/0x30 net/socket.c:1139
 __fput+0x275/0x7a0 fs/file_table.c:210
 ____fput+0x16/0x20 fs/file_table.c:244
 task_work_run+0x114/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1da/0x220 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4bc/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8880a08537c0
 which belongs to the cache UDPv6 of size 1728
The buggy address is located 552 bytes inside of
 1728-byte region [ffff8880a08537c0, ffff8880a0853e80)
The buggy address belongs to the page:
page:ffffea00028214c0 count:1 mapcount:0 mapping:ffff8880a0853080 index:0x0
flags: 0xfffe0000000100(slab)
raw: 00fffe0000000100 ffff8880a0853080 0000000000000000 0000000100000002
raw: ffffea00025eaf20 ffffea0002966c60 ffff8882161d2cc0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880a0853880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a0853900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880a0853980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                          ^
 ffff8880a0853a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a0853a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
IPv6: addrconf: prefix option has invalid lifetime