CVE-2023-53317
Unknown
Unknown - Not Provided
BaseFortify
Publication date: 2025-09-16
Last updated on: 2025-12-01
Assigner: kernel.org
Description
Description
In the Linux kernel, the following vulnerability has been resolved:
ext4: fix WARNING in mb_find_extent
Syzbot found the following issue:
EXT4-fs: Warning: mounting with data=journal disables delayed allocation, dioread_nolock, O_DIRECT and fast_commit support!
EXT4-fs (loop0): orphan cleanup on readonly fs
------------[ cut here ]------------
WARNING: CPU: 1 PID: 5067 at fs/ext4/mballoc.c:1869 mb_find_extent+0x8a1/0xe30
Modules linked in:
CPU: 1 PID: 5067 Comm: syz-executor307 Not tainted 6.2.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
RIP: 0010:mb_find_extent+0x8a1/0xe30 fs/ext4/mballoc.c:1869
RSP: 0018:ffffc90003c9e098 EFLAGS: 00010293
RAX: ffffffff82405731 RBX: 0000000000000041 RCX: ffff8880783457c0
RDX: 0000000000000000 RSI: 0000000000000041 RDI: 0000000000000040
RBP: 0000000000000040 R08: ffffffff82405723 R09: ffffed10053c9402
R10: ffffed10053c9402 R11: 1ffff110053c9401 R12: 0000000000000000
R13: ffffc90003c9e538 R14: dffffc0000000000 R15: ffffc90003c9e2cc
FS: 0000555556665300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000056312f6796f8 CR3: 0000000022437000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
ext4_mb_complex_scan_group+0x353/0x1100 fs/ext4/mballoc.c:2307
ext4_mb_regular_allocator+0x1533/0x3860 fs/ext4/mballoc.c:2735
ext4_mb_new_blocks+0xddf/0x3db0 fs/ext4/mballoc.c:5605
ext4_ext_map_blocks+0x1868/0x6880 fs/ext4/extents.c:4286
ext4_map_blocks+0xa49/0x1cc0 fs/ext4/inode.c:651
ext4_getblk+0x1b9/0x770 fs/ext4/inode.c:864
ext4_bread+0x2a/0x170 fs/ext4/inode.c:920
ext4_quota_write+0x225/0x570 fs/ext4/super.c:7105
write_blk fs/quota/quota_tree.c:64 [inline]
get_free_dqblk+0x34a/0x6d0 fs/quota/quota_tree.c:130
do_insert_tree+0x26b/0x1aa0 fs/quota/quota_tree.c:340
do_insert_tree+0x722/0x1aa0 fs/quota/quota_tree.c:375
do_insert_tree+0x722/0x1aa0 fs/quota/quota_tree.c:375
do_insert_tree+0x722/0x1aa0 fs/quota/quota_tree.c:375
dq_insert_tree fs/quota/quota_tree.c:401 [inline]
qtree_write_dquot+0x3b6/0x530 fs/quota/quota_tree.c:420
v2_write_dquot+0x11b/0x190 fs/quota/quota_v2.c:358
dquot_acquire+0x348/0x670 fs/quota/dquot.c:444
ext4_acquire_dquot+0x2dc/0x400 fs/ext4/super.c:6740
dqget+0x999/0xdc0 fs/quota/dquot.c:914
__dquot_initialize+0x3d0/0xcf0 fs/quota/dquot.c:1492
ext4_process_orphan+0x57/0x2d0 fs/ext4/orphan.c:329
ext4_orphan_cleanup+0xb60/0x1340 fs/ext4/orphan.c:474
__ext4_fill_super fs/ext4/super.c:5516 [inline]
ext4_fill_super+0x81cd/0x8700 fs/ext4/super.c:5644
get_tree_bdev+0x400/0x620 fs/super.c:1282
vfs_get_tree+0x88/0x270 fs/super.c:1489
do_new_mount+0x289/0xad0 fs/namespace.c:3145
do_mount fs/namespace.c:3488 [inline]
__do_sys_mount fs/namespace.c:3697 [inline]
__se_sys_mount+0x2d3/0x3c0 fs/namespace.c:3674
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Add some debug information:
mb_find_extent: mb_find_extent block=41, order=0 needed=64 next=0 ex=0/41/1@3735929054 64 64 7
block_bitmap: ff 3f 0c 00 fc 01 00 00 d2 3d 00 00 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
Acctually, blocks per group is 64, but block bitmap indicate at least has
128 blocks. Now, ext4_validate_block_bitmap() didn't check invalid block's
bitmap if set.
To resolve above issue, add check like fsck "Padding at end of block bitmap is
not set".
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | to 4.19.283 (exc) |
| linux | linux_kernel | From 4.20 (inc) to 5.4.243 (exc) |
| linux | linux_kernel | From 5.5 (inc) to 5.10.180 (exc) |
| linux | linux_kernel | From 5.11 (inc) to 5.15.112 (exc) |
| linux | linux_kernel | From 5.16 (inc) to 6.1.29 (exc) |
| linux | linux_kernel | From 6.2 (inc) to 6.2.16 (exc) |
| linux | linux_kernel | From 6.3 (inc) to 6.3.3 (exc) |
| linux | linux_kernel | 6.4 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-NVD-CWE-noinfo |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability is a warning and potential issue in the Linux kernel's ext4 filesystem related to the mb_find_extent function. It occurs because the ext4_validate_block_bitmap() function did not properly check if invalid blocks' bitmap bits were set, leading to inconsistencies between the blocks per group and the block bitmap. This could cause warnings or errors during filesystem operations, such as mounting or orphan cleanup, due to invalid block bitmap states.
How can this vulnerability impact me? :
The vulnerability can cause warnings and potential instability when mounting ext4 filesystems or during orphan cleanup on readonly filesystems. It may disable certain ext4 features like delayed allocation, dioread_nolock, O_DIRECT, and fast_commit support when mounting with data=journal. This could lead to degraded filesystem performance or unexpected behavior.
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