CVE-2022-48698 in Linux
Summary
by MITRE • 05/03/2024
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: fix memory leak when using debugfs_lookup()
When calling debugfs_lookup() the result must have dput() called on it, otherwise the memory will leak over time. Fix this up by properly calling dput().
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Analysis
by VulDB Data Team • 09/29/2025
The vulnerability identified as CVE-2022-48698 represents a memory leak condition within the Linux kernel's display subsystem, specifically affecting the amdgpu driver implementation. This issue occurs in the direct rendering manager (drm) component that handles graphics display operations for AMD hardware. The flaw manifests when the debugfs_lookup() function is invoked during kernel runtime, creating a scenario where allocated kernel memory resources are not properly released back to the system. This memory management oversight directly impacts system stability and resource utilization over extended periods of operation.
The technical root cause of this vulnerability stems from improper reference counting management within the kernel's debugfs interface implementation. When debugfs_lookup() is called to locate a debugfs entry, the function returns a reference to the corresponding dentry structure that must be explicitly released using the dput() function. Without this critical cleanup step, the reference count of the dentry structure remains elevated, preventing the kernel from reclaiming the associated memory resources. This pattern violates fundamental kernel memory management principles and creates a persistent resource leak that accumulates over time.
From an operational perspective, this vulnerability poses significant risks to systems running Linux kernels with AMD graphics hardware, particularly in server and embedded environments where long uptime periods are common. The memory leak gradually consumes available kernel memory resources, potentially leading to system performance degradation, memory exhaustion, and in extreme cases, system instability or crashes. The impact is particularly concerning for systems handling intensive graphics workloads or those operating in resource-constrained environments where memory efficiency is critical. The vulnerability affects systems using the amdgpu driver specifically, which is responsible for managing AMD Radeon graphics hardware in Linux environments.
The fix implemented for CVE-2022-48698 involves adding the proper dput() call to release the reference obtained from debugfs_lookup(). This remediation aligns with established kernel development practices and follows the principle of resource management where every acquired reference must have a corresponding release operation. The solution addresses the core issue by ensuring proper reference counting and memory deallocation, preventing the accumulation of unreleased kernel memory structures. This fix demonstrates adherence to the CWE-401 principle of "Improper Release of Memory Before Removing Last Reference" and follows ATT&CK technique T1490 for "Inhibit System Recovery" through memory exhaustion attacks.
Security implications extend beyond simple resource consumption, as this vulnerability could potentially be exploited by malicious actors to perform denial-of-service attacks against systems running affected kernel versions. The gradual nature of the memory leak makes detection challenging, as system administrators might not immediately recognize the degradation in performance as being memory-related. The vulnerability affects all Linux kernel versions containing the problematic code path, particularly those with the amdgpu driver implementation, making it a critical security update for organizations maintaining Linux-based systems with AMD graphics hardware. System administrators should prioritize applying this patch to prevent potential exploitation and maintain system stability.