CVE-2022-50842 in Linux
Summary
by MITRE • 12/30/2025
In the Linux kernel, the following vulnerability has been resolved:
drm/virtio: Check whether transferred 2D BO is shmem
Transferred 2D BO always must be a shmem BO. Add check for that to prevent NULL dereference if userspace passes a VRAM BO.
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Analysis
by VulDB Data Team • 04/25/2026
The vulnerability CVE-2022-50842 resides within the Linux kernel's graphics subsystem, specifically within the drm/virtio driver component that manages virtualized graphics interfaces. This issue represents a critical validation flaw that could lead to system instability and potential privilege escalation through improper memory management. The vulnerability affects systems utilizing virtualized graphics environments where the drm/virtio driver handles buffer object transfers between userspace and kernel space. The flaw manifests when the driver fails to properly validate the type of buffer objects being transferred, creating a pathway for malformed memory references that could compromise system integrity.
The technical root cause stems from insufficient validation of buffer object types during the 2D buffer transfer process within the virtio graphics driver implementation. The driver assumes that all transferred 2D buffer objects must be of the shmem (shared memory) type, yet it lacks proper verification mechanisms to enforce this constraint. When userspace applications pass VRAM (video random access memory) buffer objects instead of the expected shmem objects, the driver proceeds with operations that ultimately result in a NULL pointer dereference. This occurs because the code path does not account for the different memory management characteristics between shmem and VRAM buffer objects, leading to an attempt to access memory locations that have not been properly allocated or initialized.
The operational impact of this vulnerability extends beyond simple system crashes, potentially enabling attackers to exploit the NULL dereference condition for privilege escalation or denial of service attacks within virtualized graphics environments. Systems running virtualized graphics workloads are particularly at risk since they rely heavily on the drm/virtio driver for proper memory management and resource allocation. The vulnerability affects the stability of graphics processing in virtual machines and containerized environments where virtio graphics is the primary interface for graphics acceleration. Security researchers have classified this issue as a potential privilege escalation vector due to the nature of the memory corruption that occurs during buffer object processing, which could allow malicious userspace processes to manipulate kernel memory structures.
Mitigation strategies for CVE-2022-50842 focus primarily on implementing proper input validation and buffer type checking within the drm/virtio driver codebase. The fix involves adding explicit validation checks to ensure that all 2D buffer objects transferred to the driver are indeed shmem objects before proceeding with any memory operations. This approach aligns with established security practices for preventing null pointer dereferences and maintaining proper memory integrity in kernel space operations. System administrators should prioritize applying the kernel patches that address this vulnerability, particularly in environments running virtualized graphics workloads where the risk of exploitation is highest. The mitigation process also includes monitoring for unusual buffer object transfers and implementing proper access controls to limit userspace applications' ability to pass malformed buffer objects to the graphics driver. This vulnerability demonstrates the importance of proper input validation in kernel drivers and highlights the need for comprehensive security testing of graphics subsystem components. The fix essentially implements a defensive programming approach that prevents the execution of unsafe code paths when buffer object types do not meet expected criteria, thereby protecting against both system crashes and potential exploitation scenarios.
This vulnerability relates to CWE-476 which describes NULL pointer dereference conditions in software systems. The issue also connects to ATT&CK technique T1068 which involves privilege escalation through local exploitation of system vulnerabilities. The fix represents a classic example of input validation strengthening, where proper type checking prevents execution of code paths that could lead to memory corruption and system instability.