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BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x2de/0x320 fs/ext4/dir.c:69
Read of size 2 at addr ffff8801ad93d002 by task syz-executor3/7177

CPU: 1 PID: 7177 Comm: syz-executor3 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
IPVS: set_ctl: invalid protocol: 183 0.0.128.1:20003 dh
 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
IPVS: ftp: loaded support on port[0] = 21
 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:00007f96b3976c68 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f96b39776d4 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 3819:
 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
 ptlock_alloc+0x24/0x70 mm/memory.c:4728
 ptlock_init include/linux/mm.h:1796 [inline]
 pgtable_page_ctor include/linux/mm.h:1830 [inline]
 pte_alloc_one+0x59/0x100 arch/x86/mm/pgtable.c:32
 do_fault_around mm/memory.c:3602 [inline]
 do_read_fault mm/memory.c:3643 [inline]
 do_fault mm/memory.c:3748 [inline]
 handle_pte_fault mm/memory.c:3979 [inline]
 __handle_mm_fault+0x373f/0x38c0 mm/memory.c:4103
 handle_mm_fault+0x44a/0xb10 mm/memory.c:4140
 __do_page_fault+0x560/0xbe0 arch/x86/mm/fault.c:1422
 do_page_fault+0xee/0x730 arch/x86/mm/fault.c:1497
 page_fault+0x45/0x50 arch/x86/entry/entry_64.S:1151

Freed by task 3819:
 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
 ptlock_free+0x38/0x50 mm/memory.c:4737
 pte_lock_deinit include/linux/mm.h:1806 [inline]
 pgtable_page_dtor include/linux/mm.h:1838 [inline]
 ___pte_free_tlb+0x4b/0xc0 arch/x86/mm/pgtable.c:58
 __pte_free_tlb arch/x86/include/asm/pgalloc.h:73 [inline]
 free_pte_range mm/memory.c:446 [inline]
 free_pmd_range mm/memory.c:464 [inline]
 free_pud_range mm/memory.c:498 [inline]
 free_p4d_range mm/memory.c:532 [inline]
 free_pgd_range+0xa92/0xd50 mm/memory.c:612
 free_pgtables+0x270/0x330 mm/memory.c:644
 exit_mmap+0x291/0x500 mm/mmap.c:3039
 __mmput kernel/fork.c:960 [inline]
 mmput+0x223/0x6d0 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
 SYSC_exit_group kernel/exit.c:979 [inline]
 SyS_exit_group+0x1d/0x20 kernel/exit.c:977
 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 ffff8801ad93d000
 which belongs to the cache page->ptl of size 56
The buggy address is located 2 bytes inside of
 56-byte region [ffff8801ad93d000, ffff8801ad93d038)
The buggy address belongs to the page:
page:ffffea0006b64f40 count:1 mapcount:0 mapping:ffff8801ad93d000 index:0xffff8801ad93d580
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801ad93d000 ffff8801ad93d580 0000000100000001
raw: ffffea00071ba1e0 ffffea00073fc520 ffff8801dac10040 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801ad93cf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801ad93cf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801ad93d000: fb fb fb fb fb fb fb fc fc fc fc fb fb fb fb fb
                   ^
 ffff8801ad93d080: fb fb fc fc fc fc fb fb fb fb fb fb fb fc fc fc
 ffff8801ad93d100: fc fb fb fb fb fb fb fb fc fc fc fc fb fb fb fb
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