linux-cve-announce - CVE-2025-39768: net/mlx5: HWS, fix complex rules rehash error flow

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Message-ID: <2025091144-CVE-2025-39768-5590@gregkh>
Date: Thu, 11 Sep 2025 18:56:47 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-39768: net/mlx5: HWS, fix complex rules rehash error flow

From: Greg Kroah-Hartman <gregkh@...nel.org>

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

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

net/mlx5: HWS, fix complex rules rehash error flow

Moving rules from matcher to matcher should not fail.
However, if it does fail due to various reasons, the error flow
should allow the kernel to continue functioning (albeit with broken
steering rules) instead of going into series of soft lock-ups or
some other problematic behaviour.

Similar to the simple rules, complex rules rehash logic suffers
from the same problems. This patch fixes the error flow for moving
complex rules:
 - If new rule creation fails before it was even enqeued, do not
   poll for completion
 - If TIMEOUT happened while moving the rule, no point trying
   to poll for completions for other rules. Something is broken,
   completion won't come, just abort the rehash sequence.
 - If some other completion with error received, don't give up.
   Continue handling rest of the rules to minimize the damage.
 - Make sure that the first error code that was received will
   be actually returned to the caller instead of replacing it
   with the generic error code.

All the aforementioned issues stem from the same bad error flow,
so no point fixing them one by one and leaving partially broken
code - fixing them in one patch.

The Linux kernel CVE team has assigned CVE-2025-39768 to this issue.


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

	Issue introduced in 6.16 with commit 17e0accac577fd6ea2090934d71a8c6f36702a26 and fixed in 6.16.4 with commit 37d54bc28d092bc3b314da45d730f00e9d86ec2a
	Issue introduced in 6.16 with commit 17e0accac577fd6ea2090934d71a8c6f36702a26 and fixed in 6.17-rc3 with commit 4a842b1bf18a32ee0c25dd6dd98728b786a76fe4

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-2025-39768
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/mellanox/mlx5/core/steering/hws/bwc_complex.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/37d54bc28d092bc3b314da45d730f00e9d86ec2a
	https://git.kernel.org/stable/c/4a842b1bf18a32ee0c25dd6dd98728b786a76fe4