==================================================================
BUG: KASAN: use-after-free in ext4_data_block_valid+0x276/0x2d0 fs/ext4/block_validity.c:211
Read of size 8 at addr ffff8801d61cbbb0 by task syz-executor3/1848

CPU: 0 PID: 1848 Comm: syz-executor3 Not tainted 4.14.81+ #6
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xb9/0x11b lib/dump_stack.c:53
 print_address_description+0x60/0x22b mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report.cold.6+0x11b/0x2dd mm/kasan/report.c:409
 ext4_data_block_valid+0x276/0x2d0 fs/ext4/block_validity.c:211
 __check_block_validity.constprop.27+0xbc/0x200 fs/ext4/inode.c:402
 ext4_map_blocks+0xc22/0x1560 fs/ext4/inode.c:592
 ext4_getblk+0x31c/0x400 fs/ext4/inode.c:966
 ext4_bread_batch+0x78/0x330 fs/ext4/inode.c:1036
 ext4_find_entry+0x44c/0xcd0 fs/ext4/namei.c:1424
 ext4_rmdir+0x190/0xad0 fs/ext4/namei.c:2926
 vfs_rmdir2+0x21a/0x420 fs/namei.c:3901
 do_rmdir+0x2f5/0x3a0 fs/namei.c:3967
 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x4572d7
RSP: 002b:00007fffbdd1dbd8 EFLAGS: 00000207 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 0000000000000065 RCX: 00000000004572d7
RDX: 0000000000000000 RSI: 000000000070d698 RDI: 00007fffbdd1ed10
RBP: 0000000000000725 R08: 0000000000000000 R09: 0000000000000001
R10: 000000000000000a R11: 0000000000000207 R12: 00007fffbdd1ed10
R13: 0000000000e43940 R14: 0000000000000000 R15: 0000000000000003

Allocated by task 1:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc.part.1+0x4f/0xd0 mm/kasan/kasan.c:551
 slab_post_alloc_hook mm/slab.h:442 [inline]
 slab_alloc_node mm/slub.c:2723 [inline]
 slab_alloc mm/slub.c:2731 [inline]
 kmem_cache_alloc+0xe4/0x2b0 mm/slub.c:2736
 add_system_zone+0x261/0x4d0 fs/ext4/block_validity.c:85
 ext4_setup_system_zone+0x2e2/0x470 fs/ext4/block_validity.c:169
 ext4_fill_super+0x706c/0xb6b0 fs/ext4/super.c:4309
 mount_bdev+0x2ab/0x370 fs/super.c:1149
 mount_fs+0x28f/0x31a fs/super.c:1255
 vfs_kern_mount.part.9+0xce/0x4a0 fs/namespace.c:1056
 vfs_kern_mount fs/namespace.c:1038 [inline]
 do_new_mount fs/namespace.c:2561 [inline]
 do_mount+0x404/0x26e0 fs/namespace.c:2891
 SYSC_mount fs/namespace.c:3107 [inline]
 SyS_mount+0xe5/0x100 fs/namespace.c:3084
 do_mount_root init/do_mounts.c:366 [inline]
 mount_block_root+0x378/0x727 init/do_mounts.c:395
 prepare_namespace+0x1cf/0x20a init/do_mounts.c:600
 kernel_init_freeable+0x382/0x39f init/main.c:1091
 kernel_init+0xc/0x157 init/main.c:1000
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:402

Freed by task 20676:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xac/0x190 mm/kasan/kasan.c:524
 slab_free_hook mm/slub.c:1389 [inline]
 slab_free_freelist_hook mm/slub.c:1410 [inline]
 slab_free mm/slub.c:2966 [inline]
 kmem_cache_free+0x12d/0x350 mm/slub.c:2988
 ext4_release_system_zone+0x79/0x110 fs/ext4/block_validity.c:187
 ext4_setup_system_zone+0x3a4/0x470 fs/ext4/block_validity.c:151
 ext4_remount+0xf2e/0x1dc0 fs/ext4/super.c:5257
 do_remount_sb2+0x2eb/0x5f0 fs/super.c:878
 do_remount fs/namespace.c:2376 [inline]
 do_mount+0xfae/0x26e0 fs/namespace.c:2882
 SYSC_mount fs/namespace.c:3107 [inline]
 SyS_mount+0xe5/0x100 fs/namespace.c:3084
 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff8801d61cbb98
 which belongs to the cache ext4_system_zone of size 40
The buggy address is located 24 bytes inside of
 40-byte region [ffff8801d61cbb98, ffff8801d61cbbc0)
The buggy address belongs to the page:
page:ffffea00075872c0 count:1 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000100(slab)
raw: 4000000000000100 0000000000000000 0000000000000000 0000000180490049
raw: dead000000000100 dead000000000200 ffff8801d907c200 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d61cba80: fb fb fb fb fb fc fc fb fb fb fb fb fc fc fb fb
 ffff8801d61cbb00: fb fb fb fc fc fb fb fb fb fb fc fc fb fb fb fb
>ffff8801d61cbb80: fb fc fc fb fb fb fb fb fc fc fc fc fc fc fc fc
                                     ^
 ffff8801d61cbc00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801d61cbc80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
EXT4-fs (sda1): re-mounted. Opts: noblock_validity,