CVE-2022-49508 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
HID: elan: Fix potential double free in elan_input_configured
'input' is a managed resource allocated with devm_input_allocate_device(), so there is no need to call input_free_device() explicitly or there will be a double free.
According to the doc of devm_input_allocate_device(): * Managed input devices do not need to be explicitly unregistered or * freed as it will be done automatically when owner device unbinds from * its driver (or binding fails).
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 02/26/2025
The vulnerability CVE-2022-49508 represents a critical memory management flaw within the Linux kernel's HID (Human Interface Device) subsystem, specifically affecting the Elan touchpad driver implementation. This issue manifests in the elan_input_configured function where improper resource handling leads to a potential double free condition that could compromise system stability and security. The flaw occurs when the kernel attempts to manage input device resources through the devm_input_allocate_device() function, which is designed to provide automatic resource cleanup through device managed allocations. However, the code incorrectly attempts to manually free the device using input_free_device() after allocating it with the managed allocation function, creating a scenario where the same memory location gets freed twice. This type of vulnerability falls under the category of memory corruption issues that can be exploited to cause system crashes or potentially enable privilege escalation attacks, making it particularly concerning for embedded systems and devices where reliable operation is critical.
The technical implementation of this vulnerability stems from a fundamental misunderstanding of how device managed resources work within the Linux kernel's memory management framework. The devm_input_allocate_device() function provides automatic cleanup semantics through the device manager's reference counting system, meaning that when the device unbinds from its driver or binding fails, the kernel automatically calls input_free_device() on behalf of the driver. When developers explicitly call input_free_device() on a device that was allocated with devm_input_allocate_device(), they create a race condition where the same memory block gets deallocated twice, leading to memory corruption that can manifest as kernel panics, data corruption, or system instability. This error pattern aligns with CWE-415: Double Free, which is classified under the broader category of memory management errors in the Common Weakness Enumeration catalog. The vulnerability demonstrates a classic anti-pattern in kernel development where developers fail to properly understand the resource management semantics of device managed allocations, leading to improper cleanup sequences that can be exploited by malicious actors to disrupt system operation.
The operational impact of CVE-2022-49508 extends beyond simple system instability to potentially enable more serious security consequences depending on the execution context and system configuration. Systems utilizing Elan touchpads, which are commonly found in laptops, tablets, and embedded devices, become vulnerable to denial of service attacks that can cause complete system crashes or require manual intervention to restore functionality. In enterprise environments where these devices are prevalent, such vulnerabilities can lead to service disruptions, particularly in mission-critical systems where continuous operation is essential. The vulnerability affects any Linux kernel version that includes the problematic Elan driver implementation, making it widespread across various distributions and device types. From an attacker's perspective, this vulnerability could potentially be leveraged in combination with other kernel flaws to achieve privilege escalation or execute arbitrary code, especially when the affected system is running in environments where user input devices are frequently accessed or when the system is configured to allow unprivileged access to input device management functions. The ATT&CK framework categorizes this type of vulnerability under T1068: Exploitation for Privilege Escalation, as memory corruption issues can be exploited to gain elevated system privileges.
Mitigation strategies for CVE-2022-49508 focus primarily on patching the kernel to remove the redundant input_free_device() call from the elan_input_configured function, ensuring that managed resources are not explicitly freed. System administrators should prioritize applying the relevant kernel updates from their distribution vendors, particularly those that include the fix for the Elan touchpad driver. Organizations should also implement monitoring solutions to detect potential exploitation attempts through abnormal system behavior or memory corruption patterns. The fix demonstrates the importance of proper resource management in kernel development and reinforces the need for thorough code reviews focusing on device managed allocation patterns. Security teams should also consider implementing device access controls that limit the ability of unprivileged users to interact with input device drivers, reducing the attack surface for potential exploitation. Additionally, maintaining up-to-date kernel versions and regularly reviewing kernel patches for similar memory management issues can help prevent similar vulnerabilities from being introduced in future versions. The vulnerability highlights the critical importance of understanding the Linux kernel's device management subsystem and proper resource lifecycle management, particularly in security-sensitive environments where kernel-level stability and integrity are paramount.