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 were dealing here with FW error. We cant 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.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/1ce840c7a659aa53a31ef49f0271b4fd0dc10296
• https://git.kernel.org/stable/c/23a86c76a1a197e8fbbbd0ce3e826eb58c471624
• https://git.kernel.org/stable/c/5682aad0276ff9b9b0eff3188eb6a1f504d6b436