linux-cve-announce - CVE-2023-54269: SUNRPC: double free xprt

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Message-ID: <2025123000-CVE-2023-54269-6fd7@gregkh>
Date: Tue, 30 Dec 2025 13:20:35 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-54269: SUNRPC: double free xprt_ctxt while still in use

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

Description
===========

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

SUNRPC: double free xprt_ctxt while still in use

When an RPC request is deferred, the rq_xprt_ctxt pointer is moved out
of the svc_rqst into the svc_deferred_req.
When the deferred request is revisited, the pointer is copied into
the new svc_rqst - and also remains in the svc_deferred_req.

In the (rare?) case that the request is deferred a second time, the old
svc_deferred_req is reused - it still has all the correct content.
However in that case the rq_xprt_ctxt pointer is NOT cleared so that
when xpo_release_xprt is called, the ctxt is freed (UDP) or possible
added to a free list (RDMA).
When the deferred request is revisited for a second time, it will
reference this ctxt which may be invalid, and the free the object a
second time which is likely to oops.

So change svc_defer() to *always* clear rq_xprt_ctxt, and assert that
the value is now stored in the svc_deferred_req.

The Linux kernel CVE team has assigned CVE-2023-54269 to this issue.

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

	Issue introduced in 5.15.35 with commit f5e13d700a4d40ccde3d36e383f9247dcb3c1d2d and fixed in 5.15.113 with commit 7851771789e87108a92697194105ef0c9307dc5e
	Issue introduced in 5.18 with commit 773f91b2cf3f52df0d7508fdbf60f37567cdaee4 and fixed in 6.1.30 with commit fd86534872f445f54dc01e7db001e25eadf063a8
	Issue introduced in 5.18 with commit 773f91b2cf3f52df0d7508fdbf60f37567cdaee4 and fixed in 6.3.4 with commit e0c648627322a4c7e018e5c7f837c3c03e297dbb
	Issue introduced in 5.18 with commit 773f91b2cf3f52df0d7508fdbf60f37567cdaee4 and fixed in 6.4 with commit eb8d3a2c809abd73ab0a060fe971d6b9019aa3c1
	Issue introduced in 5.17.4 with commit 11fab500f86403b2ebf6795feeade6e10302e448

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-2023-54269
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:
	net/sunrpc/svc_xprt.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/7851771789e87108a92697194105ef0c9307dc5e
	https://git.kernel.org/stable/c/fd86534872f445f54dc01e7db001e25eadf063a8
	https://git.kernel.org/stable/c/e0c648627322a4c7e018e5c7f837c3c03e297dbb
	https://git.kernel.org/stable/c/eb8d3a2c809abd73ab0a060fe971d6b9019aa3c1