CVE-2022-49949 in Linux
Summary
by MITRE • 06/18/2025
In the Linux kernel, the following vulnerability has been resolved:
firmware_loader: Fix memory leak in firmware upload
In the case of firmware-upload, an instance of struct fw_upload is allocated in firmware_upload_register(). This data needs to be freed in fw_dev_release(). Create a new fw_upload_free() function in sysfs_upload.c to handle the firmware-upload specific memory frees and incorporate the missing kfree call for the fw_upload structure.
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Analysis
by VulDB Data Team • 11/30/2025
The vulnerability described in CVE-2022-49949 represents a memory management flaw within the Linux kernel's firmware loading subsystem that directly impacts system stability and resource utilization. This issue specifically affects the firmware_loader component which is responsible for handling firmware uploads to device drivers during system operation. The vulnerability manifests as a memory leak that occurs when firmware upload operations are performed through the sysfs interface, creating a persistent resource consumption problem that can degrade system performance over time. Such memory leaks are particularly concerning in embedded systems and server environments where sustained operation is critical and resource exhaustion can lead to system instability or denial of service conditions.
The technical root cause of this vulnerability lies in improper memory deallocation within the firmware upload handling code path. When firmware_upload_register() function is invoked to register a firmware upload operation, it allocates memory for a struct fw_upload data structure to maintain state information about the upload process. However, the cleanup function fw_dev_release() which is supposed to handle resource deallocation fails to properly free this specific memory structure. This creates a classic memory leak scenario where allocated kernel memory remains unreleased even after the firmware upload operation completes successfully or fails. The issue is classified under CWE-401 as a failure to release memory allocated to a resource, which is a fundamental memory management error that can accumulate over time and eventually lead to system resource exhaustion.
The operational impact of this vulnerability extends beyond simple memory consumption as it affects the overall reliability and predictability of system operations. When firmware uploads occur repeatedly, such as during system updates, driver reloads, or device initialization sequences, the accumulated memory leaks can cause progressive degradation of system performance. In high-availability environments or systems with frequent firmware operations, this memory leak could eventually lead to out-of-memory conditions that force system reboots or cause other critical failures. The vulnerability is particularly concerning because it operates at the kernel level where memory management errors can have cascading effects on system stability and security posture, potentially creating conditions that could be exploited by malicious actors to cause persistent resource exhaustion attacks.
The resolution for this vulnerability involves implementing a dedicated fw_upload_free() function within the sysfs_upload.c file to properly handle the specific memory deallocation requirements of firmware upload operations. This function ensures that the fw_upload structure allocated during firmware_upload_register() is correctly freed during the device release process, thereby preventing the memory leak from occurring. This approach aligns with the ATT&CK framework's defense evasion techniques by ensuring proper resource management and preventing potential exploitation through resource exhaustion attacks. The fix demonstrates proper kernel memory management practices that should be followed throughout the Linux kernel codebase, particularly in subsystems that handle dynamic resource allocation and deallocation. Organizations should prioritize applying this patch to maintain system stability and prevent potential exploitation scenarios where attackers might leverage memory leaks to cause system instability or denial of service conditions. The vulnerability serves as a reminder of the critical importance of proper memory management in kernel space code and the potential security implications of seemingly simple resource management errors.