CVE-2022-50830 in Linux
Summary
by MITRE • 12/30/2025
In the Linux kernel, the following vulnerability has been resolved:
auxdisplay: hd44780: Fix potential memory leak in hd44780_remove()
hd44780_probe() allocates a memory chunk for hd with kzalloc() and makes "lcd->drvdata->hd44780" point to it. When we call hd44780_remove(), we should release all relevant memory and resource. But "lcd->drvdata ->hd44780" is not released, which will lead to a memory leak.
We should release the "lcd->drvdata->hd44780" in hd44780_remove() to fix the memory leak bug.
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Analysis
by VulDB Data Team • 04/25/2026
The vulnerability identified as CVE-2022-50830 represents a memory leak issue within the Linux kernel's auxiliary display subsystem, specifically affecting the hd44780 driver implementation. This flaw resides in the auxiliary display framework responsible for controlling character-based displays using the hd44780 controller chipset, which is commonly found in embedded systems and industrial applications. The hd44780 driver interface supports various display types including alphanumeric character displays that operate through parallel or serial communication protocols, making it a critical component in embedded device ecosystems where memory management is paramount.
The technical root cause of this vulnerability stems from an incomplete resource cleanup routine within the driver's removal process. During driver initialization, the hd44780_probe() function properly allocates memory using kzalloc() for a hd44780 structure and establishes a pointer relationship through lcd->drvdata->hd44780 to reference this allocated memory block. However, when the hd44780_remove() function executes to clean up resources during driver unloading or system shutdown, it fails to release the specific memory chunk allocated for the hd44780 structure. This oversight creates a memory leak where the allocated memory remains allocated in kernel space, effectively preventing the kernel's memory manager from reclaiming and reusing this memory region. The issue manifests as a persistent memory allocation that grows with each driver instantiation and removal cycle, leading to gradual memory exhaustion over time.
The operational impact of this memory leak extends beyond simple resource wastage, particularly in embedded systems and industrial environments where memory constraints are severe and system stability is critical. In production environments, repeated driver loading and unloading operations will progressively consume available kernel memory, potentially leading to system instability, performance degradation, or even system crashes when memory exhaustion occurs. The vulnerability affects systems running Linux kernel versions where the auxiliary display subsystem is utilized, particularly those employing hardware interfaces that rely on the hd44780 controller for character display operations. This includes various industrial control systems, embedded network devices, and IoT applications that utilize character-based displays for status reporting or user interfaces.
Mitigation strategies for this vulnerability involve implementing a complete resource cleanup routine within the hd44780_remove() function to ensure proper memory deallocation. The fix requires adding a call to kfree() or equivalent deallocation function specifically targeting the lcd->drvdata->hd44780 memory reference before the driver removal process completes. System administrators should prioritize applying kernel updates that include this fix, particularly in environments where the auxiliary display subsystem is actively used. Additionally, monitoring systems for memory usage patterns can help detect potential memory leak impacts, though the recommended approach remains proactive patch management. This vulnerability aligns with CWE-401, which specifically addresses memory leaks in software systems, and represents a typical example of incomplete resource management that can be addressed through proper defensive programming practices and comprehensive driver testing protocols. The fix demonstrates the importance of maintaining consistent memory allocation and deallocation patterns throughout driver lifecycle management, aligning with ATT&CK framework techniques related to system resource exhaustion and memory management attacks that could exploit similar vulnerabilities in other kernel subsystems.