Subject: CVE-2024-42282: net: mediatek: Fix potential NULL pointer dereference in dummy net_device handling

From: Greg Kroah-Hartman <[email-masked]>

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

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

net: mediatek: Fix potential NULL pointer dereference in dummy net_device handling

Move the freeing of the dummy net_device from mtk_free_dev() to
mtk_remove().

Previously, if alloc_netdev_dummy() failed in mtk_probe(),
eth->dummy_dev would be NULL. The error path would then call
mtk_free_dev(), which in turn called free_netdev() assuming dummy_dev
was allocated (but it was not), potentially causing a NULL pointer
dereference.

By moving free_netdev() to mtk_remove(), we ensure it's only called when
mtk_probe() has succeeded and dummy_dev is fully allocated. This
addresses a potential NULL pointer dereference detected by Smatch[1].

The Linux kernel CVE team has assigned CVE-2024-42282 to this issue.

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

	Issue introduced in 6.10 with commit b209bd6d0bff and fixed in 6.10.3 with commit af6bd5c9901b
	Issue introduced in 6.10 with commit b209bd6d0bff and fixed in 6.11 with commit 16f3a28cf5f8

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-2024-42282
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/ethernet/mediatek/mtk_eth_soc.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/af6bd5c9901b13a26eaf4d57d97a813297791596
	https://git.kernel.org/stable/c/16f3a28cf5f876a7f3550d8f4c870a7b41bcfaef