syzbot

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BUG: KASAN: stack-out-of-bounds in strlcpy include/linux/string.h:300 [inline]
BUG: KASAN: stack-out-of-bounds in __ip_tunnel_create+0xca/0x6b0 net/ipv4/ip_tunnel.c:257
Write of size 20 at addr ffff8801ac427810 by task syzkaller981338/4466

CPU: 1 PID: 4466 Comm: syzkaller981338 Not tainted 4.16.0+ #2
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+0x1b9/0x29f lib/dump_stack.c:53
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0xac/0x2f5 mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 memcpy+0x37/0x50 mm/kasan/kasan.c:303
 strlcpy include/linux/string.h:300 [inline]
 __ip_tunnel_create+0xca/0x6b0 net/ipv4/ip_tunnel.c:257
 ip_tunnel_create net/ipv4/ip_tunnel.c:352 [inline]
 ip_tunnel_ioctl+0x818/0xd40 net/ipv4/ip_tunnel.c:861
 ipip_tunnel_ioctl+0x1c5/0x420 net/ipv4/ipip.c:350
 dev_ifsioc+0x43e/0xb90 net/core/dev_ioctl.c:334
 dev_ioctl+0x69a/0xcc0 net/core/dev_ioctl.c:525
 sock_ioctl+0x47e/0x680 net/socket.c:1015
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x1cf/0x1650 fs/ioctl.c:684
 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
 SYSC_ioctl fs/ioctl.c:708 [inline]
 SyS_ioctl+0x24/0x30 fs/ioctl.c:706
 do_syscall_64+0x29e/0x9d0 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x43fe19
RSP: 002b:00007ffe0f9231d8 EFLAGS: 00000213 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fe19
RDX: 0000000020000240 RSI: 00000000000089f1 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 000000000000001c R09: 00000000004002c8
R10: 000000000000001c R11: 0000000000000213 R12: 0000000000401740
R13: 00000000004017d0 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea0006b109c0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x2fffc0000000000()
raw: 02fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 ffffea0006b10101 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801ac427700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801ac427780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1
>ffff8801ac427800: f1 f1 00 00 f2 f2 00 00 00 00 00 00 00 00 00 00
                               ^
 ffff8801ac427880: 00 00 00 00 00 f1 f1 f1 f1 f8 f2 f2 f2 f3 f3 f3
 ffff8801ac427900: f3 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
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