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BUG: KASAN: use-after-free in ext4_data_block_valid+0x293/0x2e0 fs/ext4/block_validity.c:211
Read of size 8 at addr ffff88809acddd38 by task blkid/10995

CPU: 0 PID: 10995 Comm: blkid Not tainted 4.14.138 #34
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+0x138/0x19c lib/dump_stack.c:53
 print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2af mm/kasan/report.c:393
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 ext4_data_block_valid+0x293/0x2e0 fs/ext4/block_validity.c:211
 __check_block_validity.constprop.0+0xc1/0x200 fs/ext4/inode.c:401
 ext4_map_blocks+0xe74/0x17c0 fs/ext4/inode.c:591
 ext4_getblk+0x346/0x450 fs/ext4/inode.c:971
 ext4_bread_batch+0x6f/0x370 fs/ext4/inode.c:1041
 ext4_find_entry+0x466/0xd70 fs/ext4/namei.c:1441
 ext4_lookup fs/ext4/namei.c:1583 [inline]
 ext4_lookup+0x111/0x550 fs/ext4/namei.c:1559
 lookup_slow+0x226/0x440 fs/namei.c:1695
 walk_component+0x698/0x1d00 fs/namei.c:1824
 link_path_walk+0x81f/0x10a0 fs/namei.c:2153
 path_lookupat.isra.0+0xcb/0x7b0 fs/namei.c:2341
 filename_lookup+0x18e/0x380 fs/namei.c:2376
 user_path_at_empty+0x43/0x50 fs/namei.c:2630
 user_path_at include/linux/namei.h:57 [inline]
 SYSC_faccessat fs/open.c:403 [inline]
 SyS_faccessat fs/open.c:353 [inline]
 SYSC_access fs/open.c:450 [inline]
 SyS_access+0x222/0x6b0 fs/open.c:448
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x7fc6bdf2f267
RSP: 002b:00007ffccdf2a0a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000015
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc6bdf2f267
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007fc6bdf332e6
RBP: 00007ffccdf2a140 R08: 000000000000003c R09: 0000000000000000
R10: 00007ffccdfd8120 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000004 R14: 00007fc6be13a758 R15: 00007fc6bdf33931

Allocated by task 1:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529
 kasan_slab_alloc+0xf/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x780 mm/slab.c:3552
 add_system_zone+0x2b3/0x610 fs/ext4/block_validity.c:85
 ext4_setup_system_zone+0x303/0x480 fs/ext4/block_validity.c:169
 ext4_fill_super+0x71a0/0xb470 fs/ext4/super.c:4358
 mount_bdev+0x2be/0x370 fs/super.c:1134
 ext4_mount+0x35/0x40 fs/ext4/super.c:5860
 mount_fs+0x97/0x2a1 fs/super.c:1237
 vfs_kern_mount.part.0+0x5e/0x3d0 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2549 [inline]
 do_mount+0x417/0x27d0 fs/namespace.c:2879
 SYSC_mount fs/namespace.c:3095 [inline]
 SyS_mount+0xab/0x120 fs/namespace.c:3072
 do_mount_root+0x35/0x1b8 init/do_mounts.c:366
 mount_block_root+0x301/0x544 init/do_mounts.c:395
 mount_root+0x1dd/0x210 init/do_mounts.c:540
 prepare_namespace+0x1de/0x21d init/do_mounts.c:599
 kernel_init_freeable+0x514/0x532 init/main.c:1092
 kernel_init+0x12/0x162 init/main.c:999
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Freed by task 10990:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kmem_cache_free+0x83/0x2b0 mm/slab.c:3758
 ext4_release_system_zone+0x6f/0xf0 fs/ext4/block_validity.c:187
 ext4_setup_system_zone+0x3c3/0x480 fs/ext4/block_validity.c:151
 ext4_remount+0xf32/0x1f80 fs/ext4/super.c:5309
 do_remount_sb+0x15e/0x560 fs/super.c:868
 do_remount fs/namespace.c:2370 [inline]
 do_mount+0x13c9/0x27d0 fs/namespace.c:2870
 SYSC_mount fs/namespace.c:3095 [inline]
 SyS_mount+0xab/0x120 fs/namespace.c:3072
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff88809acddd20
 which belongs to the cache ext4_system_zone of size 40
The buggy address is located 24 bytes inside of
 40-byte region [ffff88809acddd20, ffff88809acddd48)
The buggy address belongs to the page:
page:ffffea00026b3740 count:1 mapcount:0 mapping:ffff88809acdd000 index:0xffff88809acddfb9
flags: 0x1fffc0000000100(slab)
raw: 01fffc0000000100 ffff88809acdd000 ffff88809acddfb9 0000000100000003
raw: ffff8880a689ba38 ffff8880a689ba38 ffff8880a689cd80 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809acddc00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809acddc80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88809acddd00: fc fc fc fc fb fb fb fb fb fc fc fb fb fb fb fb
                                        ^
 ffff88809acddd80: fc fc fb fb fb fb fb fc fc fb fb fb fb fb fc fc
 ffff88809acdde00: fb fb fb fb fb fc fc fb fb fb fb fb fc fc fb fb
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