CVE-2025-21751

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

net/mlx5: HWS, change error flow on matcher disconnect

Currently, when firmware failure occurs during matcher disconnect flow, the error flow of the function reconnects the matcher back and returns an error, which continues running the calling function and eventually frees the matcher that is being disconnected. This leads to a case where we have a freed matcher on the matchers list, which in turn leads to use-after-free and eventual crash.

This patch fixes that by not trying to reconnect the matcher back when some FW command fails during disconnect.

Note that we're dealing here with FW error. We can't overcome this problem. This might lead to bad steering state (e.g. wrong connection between matchers), and will also lead to resource leakage, as it is the case with any other error handling during resource destruction.

However, the goal here is to allow the driver to continue and not crash the machine with use-after-free error.

This vulnerability is rated as Moderate impact because exploiting it requires local privileges to manipulate hardware steering configurations and relies on an underlying firmware failure during teardown, limiting the blast radius to a local denial of service. An improper error handling routine in the Mellanox network driver allows an invalid reference to remain tracked after deallocation, which can result in a kernel crash. Supported Red Hat Enterprise Linux kernels do not include the vulnerable hardware steering implementation, leaving typical environments unaffected.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.