CVE-2022-48988

/// Technical description

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

memcg: fix possible use-after-free in memcg_write_event_control()

memcg_write_event_control() accesses the dentry->d_name of the specified

control fd to route the write call. As a cgroup interface file can't be

renamed, it's safe to access d_name as long as the specified file is a

regular cgroup file. Also, as these cgroup interface files can't be

removed before the directory, it's safe to access the parent too.

Prior to 347c4a874710 ("memcg: remove cgroup_event->cft"), there was a

call to __file_cft() which verified that the specified file is a regular

cgroupfs file before further accesses. The cftype pointer returned from

__file_cft() was no longer necessary and the commit inadvertently dropped

the file type check with it allowing any file to slip through. With the

invarients broken, the d_name and parent accesses can now race against

renames and removals of arbitrary files and cause use-after-free's.

Fix the

/// 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