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BUG: KASAN: slab-out-of-bounds in __ext4_check_dir_entry+0x2de/0x320 fs/ext4/dir.c:69
IPVS: ftp: loaded support on port[0] = 21
Read of size 2 at addr ffff8801c12ba002 by task syz-executor1/13502

CPU: 0 PID: 13502 Comm: syz-executor1 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:00007fb014959c68 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007fb01495a6d4 RCX: 0000000000454e79
RDX: 00000000200015fc RSI: 0000000020001540 RDI: 0000000000000013
RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000000a9 R14: 00000000006f3078 R15: 0000000000000000

Allocated by task 4484:
 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
 slab_post_alloc_hook mm/slab.h:443 [inline]
 slab_alloc mm/slab.c:3380 [inline]
 kmem_cache_alloc+0x11b/0x760 mm/slab.c:3540
 dup_mm kernel/fork.c:1224 [inline]
 copy_mm+0x30a/0x131f kernel/fork.c:1287
 copy_process.part.38+0x1fc7/0x4bd0 kernel/fork.c:1793
 copy_process kernel/fork.c:1606 [inline]
 _do_fork+0x1f7/0xf70 kernel/fork.c:2087
 SYSC_clone kernel/fork.c:2194 [inline]
 SyS_clone+0x37/0x50 kernel/fork.c:2188
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 11821:
 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
 __mmdrop+0x242/0x3d0 kernel/fork.c:604
 mmdrop include/linux/sched/mm.h:49 [inline]
 __mmput kernel/fork.c:970 [inline]
 mmput+0x537/0x6d0 kernel/fork.c:981
 exit_mm kernel/exit.c:544 [inline]
 do_exit+0x90a/0x1ad0 kernel/exit.c:852
 do_group_exit+0x149/0x400 kernel/exit.c:968
 get_signal+0x73a/0x16d0 kernel/signal.c:2469
 do_signal+0x90/0x1e90 arch/x86/kernel/signal.c:809
 exit_to_usermode_loop+0x258/0x2f0 arch/x86/entry/common.c:162
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:265 [inline]
 do_syscall_64+0x6ec/0x940 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8801c12ba280
 which belongs to the cache mm_struct(81:syz1) of size 1440
The buggy address is located 638 bytes to the left of
 1440-byte region [ffff8801c12ba280, ffff8801c12ba820)
The buggy address belongs to the page:
page:ffffea000704ae80 count:1 mapcount:0 mapping:ffff8801c12ba280 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801c12ba280 0000000000000000 0000000100000004
raw: ffffea000728ada0 ffffea0006185120 ffff8801ac7edc40 ffff8801d9774a00
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff8801d9774a00

Memory state around the buggy address:
 ffff8801c12b9f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801c12b9f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801c12ba000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff8801c12ba080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801c12ba100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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