linux-cve-announce - CVE-2022-50410: NFSD: Protect against send buffer overflow in NFSv2 READ

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Message-ID: <2025091853-CVE-2022-50410-edee@gregkh>
Date: Thu, 18 Sep 2025 18:04:00 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50410: NFSD: Protect against send buffer overflow in NFSv2 READ

From: Greg Kroah-Hartman <gregkh@...nel.org>

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.

The Linux kernel CVE team has assigned CVE-2022-50410 to this issue.

Affected and fixed versions
===========================

	Fixed in 5.10.220 with commit 2007867c5874134f2271eb276398208070049dd3
	Fixed in 5.15.75 with commit 2be9331ca6061bc6ea32247266f45b8b21030244
	Fixed in 5.19.17 with commit ea4c3eee0fd72fcedaa238556044825639cd3607
	Fixed in 6.0.3 with commit 1868332032eccbab8c1878a0d918193058c0a905
	Fixed in 6.1 with commit 401bc1f90874280a80b93f23be33a0e7e2d1f912

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2022-50410
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	fs/nfsd/nfsproc.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/2007867c5874134f2271eb276398208070049dd3
	https://git.kernel.org/stable/c/2be9331ca6061bc6ea32247266f45b8b21030244
	https://git.kernel.org/stable/c/ea4c3eee0fd72fcedaa238556044825639cd3607
	https://git.kernel.org/stable/c/1868332032eccbab8c1878a0d918193058c0a905
	https://git.kernel.org/stable/c/401bc1f90874280a80b93f23be33a0e7e2d1f912