CVE-2023-0615: Linux Kernel V4L2 DOS Vulnerability

CVE-2023-0615 Overview

A memory leak flaw combined with potential divide by zero and integer overflow vulnerabilities was discovered in the Linux kernel's V4L2 (Video4Linux2) and vivid test code functionality. This vulnerability occurs when a user triggers specific ioctls, such as VIDIOC_S_DV_TIMINGS. The flaw could allow a local user to crash the system if the vivid test code is enabled.

Critical Impact

Local attackers with low privileges can cause a denial of service condition by crashing the system through the vivid driver's improper input handling.

Affected Products

• Linux Kernel (versions prior to patched releases)
• Linux Kernel 6.2-rc1 through 6.2-rc5
• Systems with vivid test driver enabled

Discovery Timeline

• 2023-02-06 - CVE-2023-0615 published to NVD
• 2025-03-25 - Last updated in NVD database

Technical Details for CVE-2023-0615

Vulnerability Analysis

This vulnerability represents a combination of memory corruption flaws within the Linux kernel's V4L2 subsystem, specifically targeting the vivid test driver. The vivid driver is a virtual video device driver used primarily for testing Video4Linux2 APIs. When the driver processes timing information through the VIDIOC_S_DV_TIMINGS ioctl, improper validation of input parameters can lead to multiple dangerous conditions.

The integer overflow condition (CWE-190) occurs when arithmetic operations on timing values exceed the bounds of their data types, potentially wrapping around to unexpected values. Combined with improper input validation (CWE-20), this creates a scenario where subsequent calculations may use corrupted values, leading to memory leaks or divide-by-zero exceptions.

Root Cause

The root cause of this vulnerability lies in insufficient input validation within the vivid driver when processing DV timing parameters. The driver fails to properly validate user-supplied timing values before performing arithmetic operations, allowing malformed input to trigger integer overflows or division operations with zero denominators. This improper input validation propagates through the timing calculation logic, causing memory allocation failures that result in leaks and potential system crashes.

Attack Vector

The attack requires local access to the system with the vivid test driver enabled. An attacker with low-level privileges can exploit this vulnerability by making crafted ioctl calls to the vivid device node. The VIDIOC_S_DV_TIMINGS ioctl accepts timing parameters that, when maliciously constructed, can trigger the vulnerable code paths.

The exploitation involves sending specially crafted timing structures through the ioctl interface. When the driver attempts to process these malformed values, the integer overflow or divide-by-zero condition is triggered, leading to a kernel crash and denial of service. Since the attack requires only local access with low privileges and no user interaction, it presents a practical attack vector on systems where the vivid driver is loaded.

Detection Methods for CVE-2023-0615

Indicators of Compromise

• Kernel panic or system crashes originating from the vivid driver module
• Unexpected kernel oops messages referencing V4L2 or vivid components
• Abnormal memory consumption patterns associated with video device operations
• Repeated ioctl system calls targeting /dev/video* devices with vivid driver

Detection Strategies

• Monitor kernel logs for crash traces involving vivid, v4l2, or VIDIOC_S_DV_TIMINGS references
• Implement auditd rules to track ioctl calls to vivid device nodes
• Deploy kernel-level monitoring to detect unusual patterns of V4L2 API calls
• Configure SentinelOne endpoint protection to monitor for suspicious interactions with kernel video subsystems

Monitoring Recommendations

• Enable kernel auditing for video device access using auditctl rules
• Configure syslog alerting for kernel panic events related to video drivers
• Implement resource monitoring to detect memory leak patterns indicative of exploitation attempts

How to Mitigate CVE-2023-0615

Immediate Actions Required

• Disable the vivid test driver if not required for production operations
• Update to a patched version of the Linux kernel
• Restrict local access to systems where the vivid driver must remain enabled
• Consider using kernel module blacklisting to prevent vivid from loading

Patch Information

Organizations should apply kernel updates from their Linux distribution vendor that address this vulnerability. Refer to the Red Hat Bug Report #2166287 for detailed patch information and vendor-specific guidance. The fix involves adding proper input validation for timing parameters and bounds checking to prevent integer overflow conditions.

Workarounds

• Blacklist the vivid kernel module by adding blacklist vivid to /etc/modprobe.d/blacklist.conf
• Remove the vivid module if currently loaded using rmmod vivid
• Restrict access to video device nodes using appropriate file permissions
• Implement SELinux or AppArmor policies to limit ioctl access to video devices

# Configuration example - Disable vivid driver
# Add to /etc/modprobe.d/blacklist-vivid.conf
blacklist vivid

# Remove currently loaded vivid module
sudo rmmod vivid

# Prevent vivid from loading on boot
echo "install vivid /bin/false" | sudo tee /etc/modprobe.d/disable-vivid.conf