linux-cve-announce - CVE-2025-38089: sunrpc: handle SVC_GARBAGE during svc auth processing as auth error

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Message-ID: <2025063055-CVE-2025-38089-0a36@gregkh>
Date: Mon, 30 Jun 2025 09:29:53 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38089: sunrpc: handle SVC_GARBAGE during svc auth processing as auth error

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

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

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

sunrpc: handle SVC_GARBAGE during svc auth processing as auth error

tianshuo han reported a remotely-triggerable crash if the client sends a
kernel RPC server a specially crafted packet. If decoding the RPC reply
fails in such a way that SVC_GARBAGE is returned without setting the
rq_accept_statp pointer, then that pointer can be dereferenced and a
value stored there.

If it's the first time the thread has processed an RPC, then that
pointer will be set to NULL and the kernel will crash. In other cases,
it could create a memory scribble.

The server sunrpc code treats a SVC_GARBAGE return from svc_authenticate
or pg_authenticate as if it should send a GARBAGE_ARGS reply. RFC 5531
says that if authentication fails that the RPC should be rejected
instead with a status of AUTH_ERR.

Handle a SVC_GARBAGE return as an AUTH_ERROR, with a reason of
AUTH_BADCRED instead of returning GARBAGE_ARGS in that case. This
sidesteps the whole problem of touching the rpc_accept_statp pointer in
this situation and avoids the crash.

The Linux kernel CVE team has assigned CVE-2025-38089 to this issue.

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

	Issue introduced in 6.4 with commit 29cd2927fb914cc53b5ba4f67d2b74695c994ba4 and fixed in 6.6.95 with commit 599c489eea793821232a2f69a00fa57d82b0ac98
	Issue introduced in 6.4 with commit 29cd2927fb914cc53b5ba4f67d2b74695c994ba4 and fixed in 6.12.35 with commit 353e75b55e583635bf71cde6abcec274dba05edd
	Issue introduced in 6.4 with commit 29cd2927fb914cc53b5ba4f67d2b74695c994ba4 and fixed in 6.15.4 with commit c90459cd58bb421d275337093d8e901e0ba748dd
	Issue introduced in 6.4 with commit 29cd2927fb914cc53b5ba4f67d2b74695c994ba4 and fixed in 6.16-rc3 with commit 94d10a4dba0bc482f2b01e39f06d5513d0f75742
	Issue introduced in 6.3.4 with commit 9b59f5c4911e87264507e0934cd2bb277390c560

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-2025-38089
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.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/599c489eea793821232a2f69a00fa57d82b0ac98
	https://git.kernel.org/stable/c/353e75b55e583635bf71cde6abcec274dba05edd
	https://git.kernel.org/stable/c/c90459cd58bb421d275337093d8e901e0ba748dd
	https://git.kernel.org/stable/c/94d10a4dba0bc482f2b01e39f06d5513d0f75742