CVE-2026-74393 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/syncobj: Fix memory leak in drm_syncobj_find_fence()
Commit 18226ba52159 ("drm/syncobj: reject invalid flags in drm_syncobj_find_fence") forgot to take into account the fact that drm_syncobj_find() takes a reference to syncobj and returns early without dropping the reference, leading to memory leaks.
Reported by: Sam Spencer <[email protected]>
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability resides within the linux kernel's direct rendering manager subsystem specifically in the syncobj component which handles synchronization objects for graphics operations. This memory leak occurs during the execution of drm_syncobj_find_fence() function where improper reference handling leads to unreleased memory allocations. The issue was introduced in commit 18226ba52159 which attempted to enhance validation by rejecting invalid flags in drm_syncobj_find_fence() but failed to account for an existing reference management pattern within the drm_syncobj_find() function.
The technical flaw manifests when drm_syncobj_find() acquires a reference to a synchronization object and returns early without properly releasing this reference. This creates a scenario where the memory allocated for the syncobj structure remains allocated even though it should be freed, resulting in gradual memory consumption that can eventually impact system stability and performance. The function operates within the graphics subsystem context where synchronization objects are frequently created and destroyed during rendering operations, making this leak particularly problematic for systems handling intensive graphics workloads.
From an operational perspective this vulnerability represents a medium severity issue that could lead to progressive memory exhaustion on systems running graphics-intensive applications or those with high-frequency syncobj operations. The impact is amplified in embedded systems or server environments where graphics processing is frequent and memory resources are constrained. While the leak may not immediately cause system crashes, it can contribute to performance degradation over time and potentially affect other system components that rely on available memory resources.
The vulnerability aligns with CWE-401 which describes improper handling of memory allocation and deallocation, specifically referencing memory leaks that occur when references are not properly managed. This issue also relates to ATT&CK technique T1490 which covers resource exhaustion attacks where adversaries may exploit such memory management flaws to consume system resources over time. The fix requires ensuring that all reference counting mechanisms properly account for early returns from functions and maintain consistent reference semantics throughout the code path.
Mitigation strategies should focus on implementing proper reference counting practices within the drm_syncobj_find() and drm_syncobj_find_fence() functions to ensure that references are consistently released regardless of early return conditions. System administrators should monitor memory usage patterns on graphics-intensive systems and apply kernel updates promptly when available. The fix involves modifying the code path to ensure that any references acquired by drm_syncobj_find() are properly released even when the function returns early due to validation failures, maintaining consistent reference semantics throughout the synchronization object lifecycle.
The vulnerability demonstrates the complexity of reference management in kernel space where improper handling can lead to subtle but significant memory consumption issues. It highlights the importance of thorough code review processes that consider all possible execution paths and their impact on resource management. Given the widespread use of linux kernels in graphics processing environments, this fix represents an important stability enhancement for systems ranging from desktop computers to embedded devices relying on direct rendering manager functionality.
Security researchers should monitor for similar reference counting issues in other kernel subsystems where early returns might bypass proper cleanup operations. The fix serves as a reminder that validation routines must not only check input parameters but also maintain consistent resource management practices throughout the execution flow. This vulnerability underscores the critical need for comprehensive testing of edge cases and early return scenarios in kernel code to prevent memory leaks that can accumulate over time and impact system reliability.