linux-cve-announce - CVE-2024-57843: virtio-net: fix overflow inside virtnet_rq

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Message-ID: <2025011103-CVE-2024-57843-1c15@gregkh>
Date: Sat, 11 Jan 2025 15:31:03 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-57843: virtio-net: fix overflow inside virtnet_rq_alloc

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

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

virtio-net: fix overflow inside virtnet_rq_alloc

When the frag just got a page, then may lead to regression on VM.
Specially if the sysctl net.core.high_order_alloc_disable value is 1,
then the frag always get a page when do refill.

Which could see reliable crashes or scp failure (scp a file 100M in size
to VM).

The issue is that the virtnet_rq_dma takes up 16 bytes at the beginning
of a new frag. When the frag size is larger than PAGE_SIZE,
everything is fine. However, if the frag is only one page and the
total size of the buffer and virtnet_rq_dma is larger than one page, an
overflow may occur.

The commit f9dac92ba908 ("virtio_ring: enable premapped mode whatever
use_dma_api") introduced this problem. And we reverted some commits to
fix this in last linux version. Now we try to enable it and fix this
bug directly.

Here, when the frag size is not enough, we reduce the buffer len to fix
this problem.

The Linux kernel CVE team has assigned CVE-2024-57843 to this issue.

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

	Fixed in 6.6.66 with commit a8f7d6963768b114ec9644ff0148dde4c104e84b
	Fixed in 6.12.5 with commit 67a11de8965c2ab19e215fb6651d44847e068614
	Fixed in 6.13-rc1 with commit 6aacd1484468361d1d04badfe75f264fa5314864

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-2024-57843
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:
	drivers/net/virtio_net.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/a8f7d6963768b114ec9644ff0148dde4c104e84b
	https://git.kernel.org/stable/c/67a11de8965c2ab19e215fb6651d44847e068614
	https://git.kernel.org/stable/c/6aacd1484468361d1d04badfe75f264fa5314864