CVE-2022-50622

Vulnerability

In the Linux kernel's ext4 filesystem, the function ext4_fc_record_modified_inode() uses krealloc to resize a buffer (state->fc_modified_inodes). However, if krealloc fails and returns NULL, the code incorrectly sets the pointer to NULL without freeing the original memory, causing a memory leak [1][2].

Exploitation

An attacker would need to trigger a krealloc failure, which could be achieved by exhausting memory or inducing a specific allocation pattern. The vulnerability is in the fast commit path, which is used during journal commits. A local attacker with the ability to mount and interact with an ext4 filesystem could potentially exploit this to cause a denial of service via memory exhaustion [1][2].

Impact

Successful exploitation leads to a memory leak, depleting system memory over time and potentially causing a denial of service. The leak is proportional to the number of inodes modified in a transaction, making it more severe under heavy filesystem activity [1][2].

Mitigation

The issue is fixed in Linux kernel versions 4.9.337, 5.4.228, 5.10.163, 5.15.87, 6.1.5, and 6.2 with commits referenced above [1][2]. Users should apply the latest stable kernel updates to remediate this vulnerability.