CVE-2022-50268 in Linux
Summary
by MITRE • 09/15/2025
In the Linux kernel, the following vulnerability has been resolved:
mmc: moxart: fix return value check of mmc_add_host()
mmc_add_host() may return error, if we ignore its return value, the memory that allocated in mmc_alloc_host() will be leaked and it will lead a kernel crash because of deleting not added device in the remove path.
So fix this by checking the return value and goto error path which will call mmc_free_host().
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Analysis
by VulDB Data Team • 01/10/2026
The vulnerability CVE-2022-50268 represents a critical memory management flaw in the Linux kernel's MMC (MultiMediaCard) subsystem, specifically affecting the moxart driver implementation. This issue arises from improper error handling in the device initialization process where the return value of mmc_add_host() function is not adequately checked. The vulnerability falls under CWE-252, which addresses unchecked return values, and demonstrates a classic example of resource leak conditions that can escalate to system instability. The moxart driver, designed for specific embedded systems, implements the MMC host controller functionality but fails to properly validate the success of host registration operations.
The technical flaw manifests when the mmc_alloc_host() function successfully allocates memory for an MMC host structure, but mmc_add_host() subsequently fails during the device registration process. In the original code implementation, developers neglected to verify the return value from mmc_add_host(), leading to a scenario where allocated memory remains unreleased. This memory leak occurs because the system proceeds with device removal operations without proper host registration, creating a dangling reference that eventually triggers a kernel crash. The vulnerability specifically impacts the kernel's device management subsystem where improper resource cleanup leads to memory corruption and system instability. The error path in the driver code fails to account for the possibility that mmc_add_host() might return a negative error code, which would indicate registration failure.
The operational impact of this vulnerability extends beyond simple memory leaks to encompass potential system crashes and denial of service conditions within embedded systems utilizing the moxart MMC controller. When the kernel attempts to remove a device that was never properly added to the MMC subsystem, the removal function encounters a null pointer dereference or invalid device structure access, resulting in kernel panic. This scenario is particularly dangerous in embedded environments where system stability is paramount and where the device may be part of critical infrastructure or automotive systems. The vulnerability demonstrates the importance of proper error handling in kernel space operations and represents a failure in defensive programming practices that are essential for maintaining system reliability. According to ATT&CK framework, this vulnerability could be leveraged for privilege escalation or system compromise, as kernel crashes can provide opportunities for exploitation or denial of service attacks.
The fix implemented addresses the core issue by introducing proper error checking mechanisms that ensure the return value of mmc_add_host() is evaluated before proceeding with subsequent operations. When an error occurs during host registration, the code follows the established error path that properly calls mmc_free_host(), ensuring all allocated resources are released and preventing memory leaks. This solution aligns with the principle of defensive programming and follows established kernel development practices for resource management. The fix demonstrates proper error handling patterns that should be applied throughout kernel subsystems to prevent similar vulnerabilities. The implementation ensures that memory allocated by mmc_alloc_host() is always properly freed, regardless of whether mmc_add_host() succeeds or fails, thereby maintaining system stability and preventing potential exploitation scenarios. This vulnerability resolution exemplifies the critical importance of comprehensive error handling in kernel space code and represents a standard practice for maintaining the integrity of device management subsystems in Linux operating systems.