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BUG: KASAN: slab-out-of-bounds in __ext4_check_dir_entry+0x2de/0x320 fs/ext4/dir.c:69
Read of size 2 at addr ffff8801bbd28000 by task syz-executor1/26133

CPU: 0 PID: 26133 Comm: syz-executor1 Not tainted 4.16.0-rc7+ #7
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+0x194/0x24d lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report+0x23c/0x360 mm/kasan/report.c:412
 __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:431
 __ext4_check_dir_entry+0x2de/0x320 fs/ext4/dir.c:69
 ext4_readdir+0xd00/0x3600 fs/ext4/dir.c:237
 iterate_dir+0x1ca/0x530 fs/readdir.c:51
 SYSC_getdents64 fs/readdir.c:314 [inline]
 SyS_getdents64+0x221/0x420 fs/readdir.c:295
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x454e79
RSP: 002b:00007f76f4ab3c68 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f76f4ab46d4 RCX: 0000000000454e79
RDX: 00000000000000bc RSI: 0000000020000040 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000000a9 R14: 00000000006f3078 R15: 0000000000000000

Allocated by task 6116:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:552
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3542
 getname_flags+0xcb/0x580 fs/namei.c:138
 user_path_at_empty+0x2d/0x50 fs/namei.c:2569
 user_path_at include/linux/namei.h:57 [inline]
 vfs_statx+0xe9/0x190 fs/stat.c:185
 vfs_lstat include/linux/fs.h:3080 [inline]
 SYSC_newlstat+0x87/0xf0 fs/stat.c:350
 SyS_newlstat+0x1d/0x30 fs/stat.c:344
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 6116:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
 __cache_free mm/slab.c:3486 [inline]
 kmem_cache_free+0x83/0x2a0 mm/slab.c:3744
 putname+0xee/0x130 fs/namei.c:258
 filename_lookup+0x315/0x500 fs/namei.c:2324
 user_path_at_empty+0x40/0x50 fs/namei.c:2569
 user_path_at include/linux/namei.h:57 [inline]
 vfs_statx+0xe9/0x190 fs/stat.c:185
 vfs_lstat include/linux/fs.h:3080 [inline]
 SYSC_newlstat+0x87/0xf0 fs/stat.c:350
 SyS_newlstat+0x1d/0x30 fs/stat.c:344
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8801bbd28880
 which belongs to the cache names_cache of size 4096
The buggy address is located 2176 bytes to the left of
 4096-byte region [ffff8801bbd28880, ffff8801bbd29880)
The buggy address belongs to the page:
page:ffffea0006ef4a00 count:1 mapcount:0 mapping:ffff8801bbd28880 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801bbd28880 0000000000000000 0000000100000001
raw: ffffea000708f9a0 ffffea00070b3b20 ffff8801da5e9600 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801bbd27f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801bbd27f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801bbd28000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff8801bbd28080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801bbd28100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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