CVE-2022-50886 in Linux
Summary
by MITRE • 12/30/2025
In the Linux kernel, the following vulnerability has been resolved:
mmc: toshsd: 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(), besides, free_irq() also needs be called.
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Analysis
by VulDB Data Team • 04/26/2026
The vulnerability identified as CVE-2022-50886 resides within the Linux kernel's multimedia card subsystem, specifically affecting the toshsd driver implementation. This flaw represents a critical memory management issue that arises from improper error handling during device initialization processes. The vulnerability manifests when the mmc_add_host() function fails to properly validate its return status, creating a scenario where allocated memory resources remain unreleased and ultimately lead to system instability. The toshsd driver, designed to handle Toshiba SD card controllers, operates within the broader mmc (multi-media card) framework that manages various storage and memory card interfaces across embedded systems and mobile devices.
The technical root cause of this vulnerability stems from a fundamental programming error in the device initialization sequence where the return value from mmc_add_host() is completely disregarded. When mmc_add_host() encounters an error condition during host registration, it returns a negative error code that should be checked and handled appropriately. However, the flawed implementation fails to examine this return value, allowing execution to continue despite the initialization failure. This oversight results in memory allocated by mmc_alloc_host() being leaked, as the system proceeds without proper cleanup mechanisms. The memory leak compounds when the driver attempts to remove the device in error paths, as it tries to delete a device that was never successfully added to the system's device hierarchy, creating a double-free condition or invalid memory access that inevitably leads to kernel panic.
The operational impact of CVE-2022-50886 extends beyond simple memory leakage to encompass complete system stability risks that can be exploited by malicious actors. When the kernel crashes due to improper device removal handling, it creates a denial-of-service condition that can be leveraged for persistent system disruption. This vulnerability aligns with CWE-459, which describes "Incomplete Cleanup" in software systems, where resource management fails to properly handle error conditions. The flaw particularly affects embedded systems and mobile devices that rely on Toshiba SD card controllers, potentially compromising device availability and user data integrity. Attackers could exploit this vulnerability to cause system crashes at critical moments, making it particularly dangerous in automotive, industrial, or medical device applications where reliability is paramount. The vulnerability also relates to ATT&CK technique T1499.001, "Endpoint Denial of Service" where adversaries manipulate system resources to cause service unavailability.
The fix implemented for CVE-2022-50886 addresses the core memory management error by introducing proper return value validation and error path handling. The solution requires checking the mmc_add_host() return value immediately after function invocation and implementing a proper error handling routine that executes mmc_free_host() to release allocated memory resources. Additionally, the patch ensures that free_irq() is called during error cleanup to prevent interrupt handler resource leaks that could compound the memory management issues. This approach follows established kernel development practices for proper resource management and error handling, ensuring that all allocated resources are properly released regardless of initialization success or failure. The fix demonstrates adherence to secure coding principles that prevent resource leaks and maintain system stability under error conditions, making it consistent with industry standards for kernel-level security hardening and robust error handling mechanisms.