Linux DRM VC4 Driver Use-After-Free Fix: Stop Active Perfmon Before Destruction

From this webpage screenshot, we can extract the following key information about the vulnerability: 1. Vulnerability Description: - Title: - Description: When closing a file descriptor, the active performance monitor is not stopped. Although all performance monitors are destroyed in , the pointer to the active performance monitor ( ) remains unchanged. - Issue: If a new file descriptor is opened and several jobs with performance monitors are submitted, the driver will attempt to use to stop the active performance monitor. However, this pointer is no longer valid, as the previous process has terminated and all associated performance monitors have been destroyed and freed. 2. Fixes Implemented: - Code Changes: Checks were added in and functions to ensure the active performance monitor is stopped before being destroyed. - Code Snippets: - File Modified: Changes were made in . 3. Patch Information: - Author: Maira Canal - Submitter: Greg Kroah-Hartman - Date: October 4, 2024, and October 17, 2024 - Patch Link: https://patchwork.freedesktop.org/patch/msgid/20241004123817.890016-2-mcanal@igalia.com 4. Related Patches and Versions: - Related Patch: 65101d8c9108 - Version: v4.17+ This information provides insight into the vulnerability's context, the applied fixes, and related patch details, which are crucial for understanding the nature of the vulnerability and its remediation process.

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Linux DRM VC4 Driver Use-After-Free Fix: Stop Active Perfmon Before Destruction