==================================================================
BUG: KASAN: slab-out-of-bounds in strlen+0x83/0xa0 lib/string.c:482
Read of size 1 at addr ffff8801c33d9a98 by task syz-executor2/19320

CPU: 0 PID: 19320 Comm: syz-executor2 Not tainted 4.18.0-rc3-next-20180709+ #2
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+0x1c9/0x2b4 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+0x242/0x30d 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:2776
 find_autofs_mount.isra.5+0x98/0x2d0 fs/autofs/dev-ioctl.c:199
 autofs_dev_ioctl_open_mountpoint fs/autofs/dev-ioctl.c:244 [inline]
 autofs_dev_ioctl_openmount+0x18b/0x360 fs/autofs/dev-ioctl.c:284
 _autofs_dev_ioctl+0x68f/0x8b0 fs/autofs/dev-ioctl.c:684
 autofs_dev_ioctl+0x1b/0x30 fs/autofs/dev-ioctl.c:700
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
 __do_sys_ioctl fs/ioctl.c:709 [inline]
 __se_sys_ioctl fs/ioctl.c:707 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455e29
Code: 1d ba fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 eb b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 
RSP: 002b:00007f33993c4c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f33993c56d4 RCX: 0000000000455e29
RDX: 00000000200000c0 RSI: 8000000000009374 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004bc8fb R14: 00000000004cad78 R15: 0000000000000000

Allocated by task 19320:
 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/autofs/dev-ioctl.c:96 [inline]
 _autofs_dev_ioctl+0x1b0/0x8b0 fs/autofs/dev-ioctl.c:630
 autofs_dev_ioctl+0x1b/0x30 fs/autofs/dev-ioctl.c:700
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
 ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
 __do_sys_ioctl fs/ioctl.c:709 [inline]
 __se_sys_ioctl fs/ioctl.c:707 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 2417:
 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
 kobject_uevent_env+0x275/0x1110 lib/kobject_uevent.c:619
 kobject_synth_uevent+0xa63/0xc24 lib/kobject_uevent.c:208
 uevent_store+0x26/0x70 drivers/base/core.c:1050
 dev_attr_store+0x5e/0x90 drivers/base/core.c:770
 sysfs_kf_write+0x118/0x170 fs/sysfs/file.c:139
 kernfs_fop_write+0x2ba/0x480 fs/kernfs/file.c:316
 __vfs_write+0x117/0x9f0 fs/read_write.c:485
 vfs_write+0x1fc/0x560 fs/read_write.c:549
 ksys_write+0x101/0x260 fs/read_write.c:598
 __do_sys_write fs/read_write.c:610 [inline]
 __se_sys_write fs/read_write.c:607 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:607
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801c33d9a80
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 24 bytes inside of
 32-byte region [ffff8801c33d9a80, ffff8801c33d9aa0)
The buggy address belongs to the page:
page:ffffea00070cf640 count:1 mapcount:0 mapping:ffff8801da8001c0 index:0xffff8801c33d9fc1
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea00075dfc08 ffffea000752bdc8 ffff8801da8001c0
raw: ffff8801c33d9fc1 ffff8801c33d9000 0000000100000028 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c33d9980: fb fb fb fb fc fc fc fc 00 00 fc fc fc fc fc fc
 ffff8801c33d9a00: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8801c33d9a80: 00 00 00 fc fc fc fc fc fb fb fb fb fc fc fc fc
                            ^
 ffff8801c33d9b00: fb fb fb fb fc fc fc fc 05 fc fc fc fc fc fc fc
 ffff8801c33d9b80: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================