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BUG: KASAN: slab-out-of-bounds in __ext4_check_dir_entry+0x2f9/0x340 fs/ext4/dir.c:68
Read of size 2 at addr ffff888093a7a000 by task syz-executor.0/17468

CPU: 1 PID: 17468 Comm: syz-executor.0 Not tainted 4.14.198-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+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load2_noabort+0x68/0x70 mm/kasan/report.c:428
 __ext4_check_dir_entry+0x2f9/0x340 fs/ext4/dir.c:68
 ext4_readdir+0x7fd/0x27e0 fs/ext4/dir.c:240
 iterate_dir+0x1a0/0x5e0 fs/readdir.c:52
 SYSC_getdents fs/readdir.c:269 [inline]
 SyS_getdents+0x125/0x240 fs/readdir.c:250
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45e179
RSP: 002b:00007f3c4f102c78 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 0000000000003f80 RCX: 000000000045e179
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c
R13: 00007ffc23b9844f R14: 00007f3c4f1039c0 R15: 000000000118cf4c

Allocated by task 17197:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 kmem_cache_alloc+0x124/0x3c0 mm/slab.c:3552
 getname_flags+0xc8/0x550 fs/namei.c:138
 do_sys_open+0x1ce/0x410 fs/open.c:1075
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 17197:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 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
 do_sys_open+0x203/0x410 fs/open.c:1090
 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 ffff888093a7a140
 which belongs to the cache names_cache of size 4096
The buggy address is located 320 bytes to the left of
 4096-byte region [ffff888093a7a140, ffff888093a7b140)
The buggy address belongs to the page:
page:ffffea00024e9e80 count:1 mapcount:0 mapping:ffff888093a7a140 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffff888093a7a140 0000000000000000 0000000100000001
raw: ffffea000253e020 ffffea00014ed4a0 ffff8880aa58ccc0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888093a79f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888093a79f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888093a7a000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff888093a7a080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888093a7a100: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
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