CVE-2026-68273 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu: Fix context pstate override handling
There are several problems in the context pstate handling code.
The most serious ones are potential use-after-free and NULL pointer dereferences at context initialization time. Both are due amdgpu_ctx_init() not holding the adev->pm.stable_pstate_ctx_lock, which is otherwise used from both sysfs and the context code itself for modifying and clearing the stored context pointer.
Second issue is that context fini can trample over the pstate configuration set via sysfs. This is due the restore state (ctx->stable_pstate) being saved at context init time, and not if, or when the context actually changes the pstate. As the context exits it will therefore incorrectly restore to what was set before the sysfs override was requested.
The simplest fix is to drastically simplify how the state is tracked, by clearly defining the points at which pstate ownership is taken and released, and to handle all transitions under the correct lock.
Instead of at context init time, the previous state is saved only at the point the context overrides the current state, and is restored on context exit only if the context is still the owner of the current override state.
(cherry picked from commit 1b5e413713c0a93bc1818394d0ce49aaad21bd27)
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Analysis
by VulDB Data Team • 08/10/2026
The vulnerability in question affects the amdgpu driver within the Linux kernel, specifically addressing issues in context pstate handling that can lead to critical system instability and potential security implications. This flaw exists in the direct rendering manager subsystem responsible for managing graphics contexts on AMD GPU hardware. The core problem stems from improper synchronization mechanisms during context initialization and cleanup operations, creating race conditions that can result in memory corruption vulnerabilities.
The primary technical flaw manifests through multiple memory safety issues including potential use-after-free conditions and NULL pointer dereferences occurring during context initialization phases. These vulnerabilities arise because the amdgpu_ctx_init() function fails to acquire the adev->pm.stable_pstate_ctx_lock mutex, which serves as the primary synchronization mechanism for accessing and modifying stored context pointers from both sysfs interfaces and context code paths. This missing lock acquisition creates a race condition where concurrent access patterns can lead to dangling pointer references and memory corruption scenarios that violate fundamental memory safety principles.
A secondary but equally significant issue involves improper state restoration during context finalization operations. The current implementation incorrectly saves the previous pstate configuration at context initialization time rather than when actual modifications occur, leading to incorrect state restoration behavior. When a context exits, it attempts to restore the pstate to a value that may have been overridden by sysfs operations, causing the system to revert to an unintended power state configuration that can affect GPU performance characteristics and stability.
The vulnerability impacts the broader cybersecurity landscape by potentially enabling privilege escalation attacks through memory corruption exploits, as well as system stability issues that could lead to denial of service conditions. This flaw aligns with CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization) and CWE-416 (Use After Free) categories, representing classic race condition vulnerabilities in kernel space code. The issue also maps to ATT&CK technique T1068 (Exploitation for Privilege Escalation) through potential memory corruption exploitation pathways.
The proposed solution addresses these concerns through a simplified state tracking approach that clearly defines ownership transitions and ensures all state modifications occur under proper locking mechanisms. This fix implements a more robust design pattern where the previous state is only saved when a context actually overrides the current pstate, rather than at initialization time. The restoration process is modified to only occur if the context remains the active owner of the override state, preventing conflicts between sysfs operations and context lifecycle management.
This remediation approach directly addresses the fundamental synchronization issues by establishing clear boundaries for pstate ownership and ensuring that all transitions occur under appropriate lock protection. The fix eliminates the race conditions that could lead to memory corruption while maintaining system functionality and performance characteristics. The implementation follows established kernel development practices for concurrent access control and demonstrates proper resource management principles that align with security best practices in operating system internals.
The fix also incorporates defensive programming techniques by ensuring proper state validation before any operations occur, reducing the attack surface for potential exploitation attempts. This approach prevents unauthorized modifications to GPU power states through improper context handling while maintaining the intended functionality of both sysfs interfaces and context-based power management features. The solution's cherry-picked commit ensures compatibility with existing codebases while providing comprehensive protection against the identified vulnerabilities.
The resolution demonstrates the importance of proper locking mechanisms in kernel space programming, where missing synchronization primitives can lead to severe security implications. This vulnerability highlights the critical need for thorough testing of concurrent access patterns in system-level software and reinforces the necessity of following established security guidelines when developing kernel modules that interact with hardware resources. The fix serves as a model for addressing similar race condition issues in other kernel subsystems and emphasizes proper state management practices in multi-threaded environments.