ext4: avoid infinite loops caused by residual data
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 6.1.168, 6.6.131, 6.12.80, 6.18.21, 6.19.11
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: yes
- Technical impact: partial
Summary
In the Linux kernel, the following vulnerability has been resolved: ext4: avoid infinite loops caused by residual data On the mkdir/mknod path, when mapping logical blocks to physical blocks, if inserting a new extent into the extent tree fails (in this example, because the file system disabled the huge file feature when marking the inode as dirty), ext4_ext_map_blocks() only calls ext4_free_blocks() to reclaim the physical block without deleting the corresponding data in the extent tree. This causes subsequent mkdir operations to reference the previously reclaimed physical block number again, even though this physical block is already being used by the xattr block. Therefore, a situation arises where both the directory and xattr are using the same buffer head block in memory simultaneously. The above causes ext4_xattr_block_set() to enter an infinite loop about "inserted" and cannot release the inode lock, ultimately leading to the 143s blocking problem mentioned in [1]. If the metadata is corrupted, then trying to remove some extent space can do even more harm. Also in case EXT4_GET_BLOCKS_DELALLOC_RESERVE was passed, remove space wrongly update quota information. Jan Kara suggests distinguishing between two cases: 1) The error is ENOSPC or EDQUOT - in this case the filesystem is fully consistent and we must maintain its consistency including all the accounting. However these errors can happen only early before we've inserted the extent into the extent tree. So current code works correctly for this case. 2) Some other error - this means metadata is corrupted. We should strive to do as few modifications as possible to limit damage. So I'd just skip freeing of allocated blocks. [1] INFO: task syz.0.17:5995 blocked for more than 143 seconds. Call Trace: inode_lock_nested include/linux/fs.h:1073 [inline] __start_dirop fs/namei.c:2923 [inline] start_dirop fs/namei.c:2934 [inline]
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: yes · Technical impact: partial
- Record last updated
Affected versions
- Linux Linux
From 315054f023d28ee64f308adf8b5737831541776b · fixed in c66545e83a802c3851d9be27a41c0479dd29ff0c; From 315054f023d28ee64f308adf8b5737831541776b · fixed in ecc50bfca9b5c2ee6aeef998181689b80477367b; From 315054f023d28ee64f308adf8b5737831541776b · fixed in 3a7667595bcad84da53fc156a418e110267c3412; From 315054f023d28ee64f308adf8b5737831541776b · fixed in 416c86f30f91b4fb2642ef6b102596ca898f41a5; From 315054f023d28ee64f308adf8b5737831541776b · fixed in 64f425b06b3bea9abc8977fd3982779b3ad070c9; From 315054f023d28ee64f308adf8b5737831541776b · fixed in 5422fe71d26d42af6c454ca9527faaad4e677d6c
- Linux Linux
2.6.22
- KernelLinux
From 2.6.22 · fixed in 6.1.168; From 6.2.0 · fixed in 6.6.131; From 6.7.0 · fixed in 6.12.80; From 6.13.0 · fixed in 6.18.21; From 6.19.0 · fixed in 6.19.11