CVE-2025-37785

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

ext4: fix OOB read when checking dotdot dir

Mounting a corrupted filesystem with directory which contains '.' dir

entry with rec_len == block size results in out-of-bounds read (later

on, when the corrupted directory is removed).

ext4_empty_dir() assumes every ext4 directory contains at least '.'

and '..' as directory entries in the first data block. It first loads

the '.' dir entry, performs sanity checks by calling ext4_check_dir_entry()

and then uses its rec_len member to compute the location of '..' dir

entry (in ext4_next_entry). It assumes the '..' dir entry fits into the

same data block.

If the rec_len of '.' is precisely one block (4KB), it slips through the

sanity checks (it is considered the last directory entry in the data

block) and leaves "struct ext4_dir_entry_2 *de" point exactly past the

memory slot allocated to the data block. The following call to

ext4_check_dir_entry() on new value of de then der

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References