CVE-2022-50858 in Linux
Summary
by MITRE • 12/30/2025
In the Linux kernel, the following vulnerability has been resolved:
mmc: alcor: 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 calling mmc_free_host() in the error path.
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Analysis
by VulDB Data Team • 04/26/2026
The vulnerability identified as CVE-2022-50858 represents a critical memory management flaw within the Linux kernel's multimedia card host controller driver implementation. This issue specifically affects the alcor mmc driver which handles multimedia card operations in embedded systems and mobile devices. The vulnerability stems from improper error handling in the device initialization sequence where the return value from mmc_add_host() function is not properly validated. When this function encounters an error during device registration, it returns a negative error code that signals the failure to add the host controller to the system's device tree. The failure to check this return value creates a dangerous condition where the kernel continues execution despite the initialization failure, leading to resource management complications that can escalate to system instability.
The technical flaw manifests in the improper handling of memory allocation and device registration sequences within the mmc subsystem. During normal operation, mmc_alloc_host() allocates memory structures necessary for host controller management, but when mmc_add_host() fails to register the device, the allocated memory remains unreleased and becomes orphaned within the kernel's memory management system. This memory leak occurs because the driver does not implement proper error recovery paths that would invoke mmc_free_host() to clean up the allocated resources when initialization fails. The consequence of this oversight becomes apparent during device removal operations where the kernel attempts to delete a device that was never properly added to the system's device list, causing a kernel panic or system crash. This represents a classic case of resource leak leading to system instability, with the failure path directly correlating to improper error handling and memory management practices.
The operational impact of this vulnerability extends beyond simple memory leaks to potentially compromise system stability and availability in embedded and mobile environments where multimedia card functionality is essential. Systems utilizing the alcor mmc driver, particularly those in automotive, industrial, or mobile computing contexts, face risk of unexpected system crashes or reboots when multimedia card operations are attempted. The vulnerability affects the kernel's ability to maintain consistent device state management and can lead to denial of service conditions where the system becomes unstable under normal usage patterns. Attackers could potentially exploit this vulnerability to cause persistent system crashes or to create conditions that might be leveraged for more sophisticated attacks. The vulnerability is particularly concerning in embedded systems where kernel stability is paramount for operational reliability and safety-critical applications.
Mitigation strategies for CVE-2022-50858 focus on implementing proper error handling and resource management within the affected driver code. The fix involves modifying the alcor mmc driver to check the return value of mmc_add_host() and ensure that mmc_free_host() is called in error paths to prevent memory leaks and maintain proper device state management. This approach aligns with established security practices and follows the principle of defensive programming where all function calls that can fail are properly validated. The solution also demonstrates adherence to common weakness enumeration standards where CWE-459 represents incomplete cleanup or resource leak, while the attack pattern aligns with techniques described in MITRE ATT&CK framework under system compromise and privilege escalation categories. System administrators should prioritize applying kernel updates that include this fix, particularly in environments where multimedia card functionality is critical, and implement monitoring to detect potential system instability that might indicate exploitation attempts. Regular kernel security audits should include verification of error handling patterns across all device drivers to prevent similar issues from emerging in other subsystems.