==================================================================
BUG: KASAN: slab-out-of-bounds in __ext4_check_dir_entry+0x2f9/0x340 fs/ext4/dir.c:68
Read of size 2 at addr ffff88820adae001 by task syz-executor.4/13835

CPU: 0 PID: 13835 Comm: syz-executor.4 Not tainted 4.14.184-syzkaller #0
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+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1dc 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+0xa9/0x2b9 mm/kasan/report.c:393
 __ext4_check_dir_entry+0x2f9/0x340 fs/ext4/dir.c:68
 ext4_readdir+0x819/0x27e0 fs/ext4/dir.c:240
 iterate_dir+0x1a0/0x5e0 fs/readdir.c:52
 SYSC_getdents fs/readdir.c:269 [inline]
 SyS_getdents+0x132/0x260 fs/readdir.c:250
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45cba9
RSP: 002b:00007f6475efcc78 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 00000000004ddbc0 RCX: 000000000045cba9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000000fb R14: 00000000004c3bb1 R15: 00007f6475efd6d4

Allocated by task 6351:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc.part.0+0x4f/0xd0 mm/kasan/kasan.c:551
 kmem_cache_alloc+0x124/0x3c0 mm/slab.c:3552
 getname_flags+0xc8/0x550 fs/namei.c:138
 getname fs/namei.c:209 [inline]
 user_path_mountpoint_at+0x23/0x40 fs/namei.c:2775
 SYSC_umount fs/namespace.c:1730 [inline]
 SyS_umount+0x11b/0xc00 fs/namespace.c:1714
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 6351:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xaf/0x190 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kmem_cache_free+0x7c/0x2b0 mm/slab.c:3758
 putname+0xcd/0x110 fs/namei.c:259
 filename_mountpoint+0x218/0x320 fs/namei.c:2753
 SYSC_umount fs/namespace.c:1730 [inline]
 SyS_umount+0x11b/0xc00 fs/namespace.c:1714
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff88820adaeb40
 which belongs to the cache names_cache of size 4096
The buggy address is located 2879 bytes to the left of
 4096-byte region [ffff88820adaeb40, ffff88820adafb40)
The buggy address belongs to the page:
page:ffffea00082b6b80 count:1 mapcount:0 mapping:ffff88820adaeb40 index:0x0 compound_mapcount: 0
flags: 0x57ffe0000008100(slab|head)
raw: 057ffe0000008100 ffff88820adaeb40 0000000000000000 0000000100000001
raw: ffffea00083fc420 ffffea00081a88a0 ffff8880aa9dacc0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88820adadf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88820adadf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88820adae000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff88820adae080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88820adae100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.1'.