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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 ffff8801bd700002 by task syz-executor2/19680

CPU: 1 PID: 19680 Comm: syz-executor2 Not tainted 4.16.0-rc7+ #9
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:00007f5712603c68 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f57126046d4 RCX: 0000000000454e79
RDX: 00000000200015fc RSI: 0000000020001540 RDI: 0000000000000014
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000000a9 R14: 00000000006f3078 R15: 0000000000000000

Allocated by task 19265:
 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_kernel+0x54/0x340 fs/namei.c:218
 open_exec+0x17/0x60 fs/exec.c:877
 load_elf_binary+0x1348/0x4c10 fs/binfmt_elf.c:775
 search_binary_handler+0x142/0x6b0 fs/exec.c:1638
 exec_binprm fs/exec.c:1680 [inline]
 do_execveat_common.isra.30+0x1754/0x23c0 fs/exec.c:1802
 do_execve fs/exec.c:1847 [inline]
 SYSC_execve fs/exec.c:1928 [inline]
 SyS_execve+0x39/0x50 fs/exec.c:1923
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 19265:
 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
 open_exec+0x41/0x60 fs/exec.c:882
 load_elf_binary+0x1348/0x4c10 fs/binfmt_elf.c:775
 search_binary_handler+0x142/0x6b0 fs/exec.c:1638
 exec_binprm fs/exec.c:1680 [inline]
 do_execveat_common.isra.30+0x1754/0x23c0 fs/exec.c:1802
 do_execve fs/exec.c:1847 [inline]
 SYSC_execve fs/exec.c:1928 [inline]
 SyS_execve+0x39/0x50 fs/exec.c:1923
 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 ffff8801bd700d80
 which belongs to the cache names_cache of size 4096
The buggy address is located 3454 bytes to the left of
 4096-byte region [ffff8801bd700d80, ffff8801bd701d80)
The buggy address belongs to the page:
page:ffffea0006f5c000 count:1 mapcount:0 mapping:ffff8801bd700d80 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801bd700d80 0000000000000000 0000000100000001
raw: ffffea00073d0620 ffffea0006f10c20 ffff8801da5e9600 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801bd6fff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801bd6fff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801bd700000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff8801bd700080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801bd700100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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