Linux Kernel up to 5.12.2 mhi mhi_queue use after free

Summaryinfo

A vulnerability identified as critical has been detected in Linux Kernel up to 5.12.2. This affects the function mhi_queue of the component mhi. Performing a manipulation results in use after free. This vulnerability is cataloged as CVE-2021-46969. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 5.12.2 (Operating System). It has been classified as critical. This affects the function mhi_queue of the component mhi. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: bus: mhi: core: Fix invalid error returning in mhi_queue mhi_queue returns an error when the doorbell is not accessible in the current state. This can happen when the device is in non M0 state, like M3, and needs to be waken-up prior ringing the DB. This case is managed earlier by triggering an asynchronous M3 exit via controller resume/suspend callbacks, that in turn will cause M0 transition and DB update. So, since it's not an error but just delaying of doorbell update, there is no reason to return an error. This also fixes a use after free error for skb case, indeed a caller queuing skb will try to free the skb if the queueing fails, but in that case queueing has been done.

The weakness was shared 02/27/2024. The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2021-46969. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/10/2025).

The vulnerability scanner Nessus provides a plugin with the ID 247018 (Linux Distros Unpatched Vulnerability : CVE-2021-46969), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.12.3 or 5.13 eliminates this vulnerability. Applying the patch a99b661c3187/0ecc1c70dcd3 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at Tenable (247018). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.12.0
• 5.12.1
• 5.12.2

License

• open-source

Website

• Vendor: https://www.kernel.org/

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If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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