Subject: CVE-2024-50020: ice: Fix improper handling of refcount in ice_sriov_set_msix_vec_count()

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

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

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

ice: Fix improper handling of refcount in ice_sriov_set_msix_vec_count()

This patch addresses an issue with improper reference count handling in the
ice_sriov_set_msix_vec_count() function.

First, the function calls ice_get_vf_by_id(), which increments the
reference count of the vf pointer. If the subsequent call to
ice_get_vf_vsi() fails, the function currently returns an error without
decrementing the reference count of the vf pointer, leading to a reference
count leak. The correct behavior, as implemented in this patch, is to
decrement the reference count using ice_put_vf(vf) before returning an
error when vsi is NULL.

Second, the function calls ice_sriov_get_irqs(), which sets
vf->first_vector_idx. If this call returns a negative value, indicating an
error, the function returns an error without decrementing the reference
count of the vf pointer, resulting in another reference count leak. The
patch addresses this by adding a call to ice_put_vf(vf) before returning
an error when vf->first_vector_idx < 0.

This bug was identified by an experimental static analysis tool developed
by our team. The tool specializes in analyzing reference count operations
and identifying potential mismanagement of reference counts. In this case,
the tool flagged the missing decrement operation as a potential issue,
leading to this patch.

The Linux kernel CVE team has assigned CVE-2024-50020 to this issue.

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

	Issue introduced in 6.7 with commit 4d38cb44bd32 and fixed in 6.11.4 with commit 416dbb815ca6
	Issue introduced in 6.7 with commit 4d38cb44bd32 and fixed in 6.12-rc3 with commit d517cf89874c
	Issue introduced in 6.7.10 with commit 3345e7cf0cf8

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-2024-50020
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/intel/ice/ice_sriov.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/416dbb815ca69684de148328990ba0ec53e6dbc1
	https://git.kernel.org/stable/c/d517cf89874c6039e6294b18d66f40988e62502a