CVE-2022-50786 in Linux
Summary
by MITRE • 12/30/2025
In the Linux kernel, the following vulnerability has been resolved:
media: s5p-mfc: Clear workbit to handle error condition
During error on CLOSE_INSTANCE command, ctx_work_bits was not getting cleared. During consequent mfc execution NULL pointer dereferencing of this context led to kernel panic. This patch fixes this issue by making sure to clear ctx_work_bits always.
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Analysis
by VulDB Data Team • 01/06/2026
The vulnerability described in CVE-2022-50786 resides within the Linux kernel's multimedia framework, specifically affecting the s5p-mfc driver which handles multimedia codec operations on Samsung SoC platforms. This issue represents a critical flaw in the kernel's error handling mechanism that can lead to system instability and potential denial of service conditions. The s5p-mfc driver is responsible for managing multimedia codec instances on Samsung's Multi Media Framework hardware, making it a crucial component for devices that process video and audio content. The vulnerability manifests when the driver fails to properly clear internal state flags during error conditions, creating a scenario where subsequent operations can trigger kernel-level failures.
The technical flaw occurs within the CLOSE_INSTANCE command processing logic where the ctx_work_bits variable, which serves as a work bit flag for tracking codec context states, fails to be cleared when an error condition occurs during instance closure. This variable acts as a state indicator that the kernel uses to track the operational status of multimedia codec contexts. When the error handling path is executed, the work bit remains set even though the context structure may have been invalidated or deallocated, creating a scenario where the driver continues to reference stale or NULL context pointers. The root cause stems from improper state management in the driver's error recovery code, where the cleanup routine fails to properly reset the work bit flag before proceeding with other operations.
The operational impact of this vulnerability is severe, as it can lead to immediate kernel panic conditions when subsequent multimedia operations attempt to access the corrupted context structure. The NULL pointer dereference that results from this condition causes the kernel to crash and reboot the system, effectively creating a denial of service vulnerability that can be exploited by malicious actors to disrupt system operations. This vulnerability is particularly concerning in embedded systems and mobile devices where the s5p-mfc driver is commonly used for video playback, recording, and streaming operations. The vulnerability can be triggered through normal multimedia operations, making it a persistent threat to system stability and reliability. According to CWE classification, this represents a CWE-476: NULL Pointer Dereference vulnerability, which is categorized under the broader category of memory safety issues. The ATT&CK framework would classify this under T1499.004: Endpoint Denial of Service, as it enables an attacker to cause system instability and potential service disruption.
The patch implemented to address this vulnerability ensures that ctx_work_bits is always cleared regardless of whether the CLOSE_INSTANCE command succeeds or fails, providing proper state management throughout the driver's lifecycle. This fix aligns with the principle of defensive programming where all state variables are properly initialized and cleared to prevent undefined behavior. The mitigation strategy focuses on ensuring that error recovery paths in the driver properly clean up all internal state flags before allowing subsequent operations to proceed. This vulnerability highlights the importance of proper error handling in kernel drivers and demonstrates how seemingly minor state management issues can lead to critical system failures. The fix represents a straightforward but essential correction that ensures the driver maintains consistent internal state throughout its operational lifecycle, preventing the cascade of errors that could lead to system crashes. Organizations should prioritize applying this patch to all systems utilizing the s5p-mfc driver, particularly in environments where multimedia operations are frequent and system stability is critical.