CVE-2026-74706: bnge: Fix NULL pointer dereference in aux device release

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

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

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

bnge: Fix NULL pointer dereference in aux device release

If allocation of auxr_dev fails during auxiliary device setup, the error
path calls auxiliary_device_uninit(), which eventually invokes
bnge_aux_dev_release().

The release callback unconditionally dereferences aux_priv->auxr_dev->pdev
to retrieve the parent bnge_dev. Since auxr_dev has not yet been allocated
on this failure path, the dereference results in a NULL pointer exception

Retrieve the parent bnge_dev from the auxiliary device's parent instead of
auxr_dev, and free auxr_dev only when it was successfully allocated. This
allows the release callback to correctly clean up partially initialized
auxiliary devices.

The Linux kernel CVE team has assigned CVE-2026-74706 to this issue.


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

	Issue introduced in 6.19 with commit 8ac050ec3b1c0dcb5e89cf86fe2ebe0afcc73554 and fixed in 7.1.9 with commit 83ef2f3cab7fe6dd9155cd598dc64be524d963a9
	Issue introduced in 6.19 with commit 8ac050ec3b1c0dcb5e89cf86fe2ebe0afcc73554 and fixed in 7.2 with commit 1cb4298810e27e037d3ca07286ecbb97e89ba58d

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-2026-74706
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/broadcom/bnge/bnge_auxr.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/83ef2f3cab7fe6dd9155cd598dc64be524d963a9
	https://git.kernel.org/stable/c/1cb4298810e27e037d3ca07286ecbb97e89ba58d