CVE-2024-50263

/// Technical description

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

fork: only invoke khugepaged, ksm hooks if no error

There is no reason to invoke these hooks early against an mm that is in an

incomplete state.

The change in commit d24062914837 ("fork: use __mt_dup() to duplicate

maple tree in dup_mmap()") makes this more pertinent as we may be in a

state where entries in the maple tree are not yet consistent.

Their placement early in dup_mmap() only appears to have been meaningful

for early error checking, and since functionally it'd require a very small

allocation to fail (in practice 'too small to fail') that'd only occur in

the most dire circumstances, meaning the fork would fail or be OOM'd in

any case.

Since both khugepaged and KSM tracking are there to provide optimisations

to memory performance rather than critical functionality, it doesn't

really matter all that much if, under such dire memory pressure, we fail

to register an mm with these.

As a result, we follow the e

/// 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