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BUG: KASAN: slab-out-of-bounds in strlen+0x83/0xa0 lib/string.c:482
Read of size 1 at addr ffff8801d924a198 by task syz-executor1/14601

CPU: 1 PID: 14601 Comm: syz-executor1 Not tainted 4.17.0-rc7+ #78
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430
 strlen+0x83/0xa0 lib/string.c:482
 strlen include/linux/string.h:267 [inline]
 getname_kernel+0x24/0x370 fs/namei.c:218
 kern_path_mountpoint+0x23/0x40 fs/namei.c:2706
 find_autofs_mount.isra.5+0x8c/0x2b0 fs/autofs4/dev-ioctl.c:212
 autofs_dev_ioctl_open_mountpoint fs/autofs4/dev-ioctl.c:257 [inline]
 autofs_dev_ioctl_openmount+0x183/0x340 fs/autofs4/dev-ioctl.c:297
 _autofs_dev_ioctl+0x67a/0x890 fs/autofs4/dev-ioctl.c:697
 autofs_dev_ioctl+0x1b/0x30 fs/autofs4/dev-ioctl.c:713
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x1cf/0x16a0 fs/ioctl.c:684
 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
 __do_sys_ioctl fs/ioctl.c:708 [inline]
 __se_sys_ioctl fs/ioctl.c:706 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455a09
RSP: 002b:00007f7d58395c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f7d583966d4 RCX: 0000000000455a09
RDX: 0000000020000080 RSI: 8000000000009374 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 000000000000018f R14: 00000000006f7608 R15: 0000000000000000

Allocated by task 14601:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 __do_kmalloc mm/slab.c:3718 [inline]
 __kmalloc_track_caller+0x14a/0x760 mm/slab.c:3733
 memdup_user+0x2c/0xa0 mm/util.c:160
 copy_dev_ioctl fs/autofs4/dev-ioctl.c:109 [inline]
 _autofs_dev_ioctl+0x1a8/0x890 fs/autofs4/dev-ioctl.c:643
 autofs_dev_ioctl+0x1b/0x30 fs/autofs4/dev-ioctl.c:713
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x1cf/0x16a0 fs/ioctl.c:684
 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:701
 __do_sys_ioctl fs/ioctl.c:708 [inline]
 __se_sys_ioctl fs/ioctl.c:706 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:706
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 11047:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kfree+0xd9/0x260 mm/slab.c:3813
 kvfree+0x61/0x70 mm/util.c:440
 xt_free_table_info+0xb7/0x180 net/netfilter/x_tables.c:1202
 __do_replace+0x85d/0xac0 net/ipv6/netfilter/ip6_tables.c:1107
 do_replace net/ipv6/netfilter/ip6_tables.c:1160 [inline]
 do_ip6t_set_ctl+0x49c/0x64b net/ipv6/netfilter/ip6_tables.c:1684
 nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
 nf_setsockopt+0x7d/0xd0 net/netfilter/nf_sockopt.c:115
 ipv6_setsockopt+0x105/0x170 net/ipv6/ipv6_sockglue.c:927
 tcp_setsockopt+0x93/0xe0 net/ipv4/tcp.c:2891
 sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3039
 __sys_setsockopt+0x1bd/0x390 net/socket.c:1903
 __do_sys_setsockopt net/socket.c:1914 [inline]
 __se_sys_setsockopt net/socket.c:1911 [inline]
 __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1911
 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801d924a180
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 24 bytes inside of
 32-byte region [ffff8801d924a180, ffff8801d924a1a0)
The buggy address belongs to the page:
page:ffffea0007649280 count:1 mapcount:0 mapping:ffff8801d924a000 index:0xffff8801d924afc1
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801d924a000 ffff8801d924afc1 000000010000003f
raw: ffffea0007645920 ffffea00076451e0 ffff8801da8001c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d924a080: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801d924a100: fb fb fb fb fc fc fc fc 00 fc fc fc fc fc fc fc
>ffff8801d924a180: 00 00 00 fc fc fc fc fc 05 fc fc fc fc fc fc fc
                            ^
 ffff8801d924a200: fb fb fb fb fc fc fc fc 05 fc fc fc fc fc fc fc
 ffff8801d924a280: fb fb fb fb fc fc fc fc 00 fc fc fc fc fc fc fc
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