CVE-2022-50410

/// Technical description

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

NFSD: Protect against send buffer overflow in NFSv2 READ

Since before the git era, NFSD has conserved the number of pages

held by each nfsd thread by combining the RPC receive and send

buffers into a single array of pages. This works because there are

no cases where an operation needs a large RPC Call message and a

large RPC Reply at the same time.

Once an RPC Call has been received, svc_process() updates

svc_rqst::rq_res to describe the part of rq_pages that can be

used for constructing the Reply. This means that the send buffer

(rq_res) shrinks when the received RPC record containing the RPC

Call is large.

A client can force this shrinkage on TCP by sending a correctly-

formed RPC Call header contained in an RPC record that is

excessively large. The full maximum payload size cannot be

constructed in that case.

/// 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