CVE-2023-31081 in Linux
Summary
by MITRE • 04/24/2023
An issue was discovered in drivers/media/test-drivers/vidtv/vidtv_bridge.c in the Linux kernel 6.2. There is a NULL pointer dereference in vidtv_mux_stop_thread. In vidtv_stop_streaming, after dvb->mux=NULL occurs, it executes vidtv_mux_stop_thread(dvb->mux).
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Analysis
by VulDB Data Team • 02/05/2025
The vulnerability identified as CVE-2023-31081 represents a critical NULL pointer dereference flaw within the Linux kernel's video television driver subsystem. This issue exists in the vidtv_bridge.c file located in the drivers/media/test-drivers/vidtv/ directory of the kernel version 6.2. The flaw manifests during the video television streaming termination process, specifically when the system attempts to stop streaming operations. The vulnerability stems from improper null pointer validation within the driver's cleanup sequence, creating a potential crash condition that could be exploited by malicious actors.
The technical implementation of this vulnerability occurs in the vidtv_mux_stop_thread function where the system executes a null pointer dereference operation. During normal operation, the vidtv_stop_streaming function sets dvb->mux to NULL as part of its cleanup routine, but subsequently calls vidtv_mux_stop_thread(dvb->mux) with this null value. This creates an immediate dereference of a NULL pointer, causing the kernel to crash or potentially allowing for privilege escalation. The flaw demonstrates poor defensive programming practices where the system fails to validate pointer states before execution, violating fundamental security principles that should be enforced in kernel-level code.
The operational impact of this vulnerability extends beyond simple system crashes to potentially enable more serious security consequences. When the kernel crashes due to this NULL pointer dereference, it creates a denial of service condition that could be exploited by attackers to disrupt critical video streaming services or embedded systems. In environments where the Linux kernel serves as a core component of multimedia processing systems, this vulnerability could be leveraged to cause system instability or even enable privilege escalation attacks. The issue affects systems using the test drivers for video television functionality, which may be present in various embedded devices, multimedia systems, and specialized hardware platforms that rely on kernel-level video processing capabilities.
This vulnerability maps directly to CWE-476 which specifically addresses NULL pointer dereference conditions in software systems. The flaw demonstrates a classic security weakness where insufficient input validation leads to system instability. From an ATT&CK framework perspective, this vulnerability could be categorized under T1499.004 for Network Denial of Service and potentially T1068 for Exploitation for Privilege Escalation if the system allows for additional exploitation paths. The attack surface is primarily limited to systems running the affected kernel version with the specific test drivers enabled, but given the widespread use of Linux kernels in embedded systems and multimedia applications, the potential impact remains significant. Organizations should prioritize patching this vulnerability through kernel updates that implement proper null pointer validation before the vidtv_mux_stop_thread function executes, ensuring that the system properly checks pointer states before attempting to dereference them. The fix should involve adding explicit null pointer checks within the vidtv_stop_streaming function to prevent execution of vidtv_mux_stop_thread when dvb->mux is already NULL, thereby preventing the crash condition and maintaining system stability.