linux-cve-announce - CVE-2024-42246: net, sunrpc: Remap EPERM in case of connection failure in xs_tcp_setup

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Message-ID: <2024080742-CVE-2024-42246-0777@gregkh>
Date: Wed,  7 Aug 2024 17:14:52 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-42246: net, sunrpc: Remap EPERM in case of connection failure in xs_tcp_setup_socket

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

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

net, sunrpc: Remap EPERM in case of connection failure in xs_tcp_setup_socket

When using a BPF program on kernel_connect(), the call can return -EPERM. This
causes xs_tcp_setup_socket() to loop forever, filling up the syslog and causing
the kernel to potentially freeze up.

Neil suggested:

  This will propagate -EPERM up into other layers which might not be ready
  to handle it. It might be safer to map EPERM to an error we would be more
  likely to expect from the network system - such as ECONNREFUSED or ENETDOWN.

ECONNREFUSED as error seems reasonable. For programs setting a different error
can be out of reach (see handling in 4fbac77d2d09) in particular on kernels
which do not have f10d05966196 ("bpf: Make BPF_PROG_RUN_ARRAY return -err
instead of allow boolean"), thus given that it is better to simply remap for
consistent behavior. UDP does handle EPERM in xs_udp_send_request().

The Linux kernel CVE team has assigned CVE-2024-42246 to this issue.

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

	Issue introduced in 4.17 with commit 4fbac77d2d09 and fixed in 6.1.100 with commit f2431e7db0fe
	Issue introduced in 4.17 with commit 4fbac77d2d09 and fixed in 6.6.41 with commit d6c686c01c5f
	Issue introduced in 4.17 with commit 4fbac77d2d09 and fixed in 6.9.10 with commit f388cfd913a2
	Issue introduced in 4.17 with commit 4fbac77d2d09 and fixed in 6.10 with commit 626dfed5fa3b

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-2024-42246
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/xprtsock.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/f2431e7db0fe0daccb2f06bb0d23740affcd2fa6
	https://git.kernel.org/stable/c/d6c686c01c5f12ff8f7264e0ddf71df6cb0d4414
	https://git.kernel.org/stable/c/f388cfd913a2b96c05339a335f365795db1b36b6
	https://git.kernel.org/stable/c/626dfed5fa3bfb41e0dffd796032b555b69f9cde