CVE-2019-19044 in Linux
Summary
by MITRE • 01/25/2023
Two memory leaks in the v3d_submit_cl_ioctl() function in drivers/gpu/drm/v3d/v3d_gem.c in the Linux kernel before 5.3.11 allow attackers to cause a denial of service (memory consumption) by triggering kcalloc() or v3d_job_init() failures, aka CID-29cd13cfd762.
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Analysis
by VulDB Data Team • 02/23/2024
The vulnerability identified as CVE-2019-19044 represents a critical memory management flaw within the Linux kernel's graphics processing unit driver subsystem, specifically affecting the VideoCore IV graphics hardware implementation. This issue resides in the v3d_submit_cl_ioctl() function located in drivers/gpu/drm/v3d/v3d_gem.c, where improper error handling leads to persistent memory resource exhaustion. The vulnerability affects Linux kernel versions prior to 5.3.11, making it a widespread concern across numerous production systems that have not yet been patched. The flaw manifests through two distinct memory leak scenarios that occur when kcalloc() or v3d_job_init() operations fail during graphics command submission processes, creating a persistent resource drain that can ultimately lead to system instability.
The technical implementation of this vulnerability stems from inadequate memory cleanup procedures within the graphics driver's command submission pipeline. When the v3d_submit_cl_ioctl() function processes graphics commands, it allocates memory structures using kcalloc() for kernel memory management. However, in failure scenarios where these allocations do not complete successfully, the driver fails to properly release previously allocated memory segments. Additionally, when v3d_job_init() operations encounter errors during job initialization, the function does not properly clean up already allocated resources, resulting in memory leaks that accumulate over time. This behavior creates a systematic degradation of available memory resources, particularly affecting systems running graphics-intensive applications or those handling multiple concurrent graphics operations. The vulnerability is classified as a memory leak under CWE-401, which specifically addresses the improper management of allocated memory resources, and directly impacts system availability through resource exhaustion.
The operational impact of CVE-2019-19044 extends beyond simple resource consumption to create significant denial of service conditions that can compromise entire system operations. Attackers can exploit this vulnerability by repeatedly submitting graphics commands that trigger the failure paths, causing progressive memory consumption that eventually leads to system instability or complete system hangs. The memory leaks accumulate silently over time, making detection challenging until the system reaches critical resource exhaustion levels. This vulnerability particularly affects embedded systems, mobile devices, and server environments that rely heavily on graphics processing capabilities, where memory resources are already constrained. The impact aligns with ATT&CK technique T1499.004, which covers resource exhaustion attacks targeting system memory, and represents a classic example of how kernel-level memory management flaws can be weaponized to create persistent denial of service conditions. Systems running older kernel versions without the relevant security patches become increasingly vulnerable as the accumulation of leaked memory resources continues.
Mitigation strategies for CVE-2019-19044 require immediate kernel version updates to 5.3.11 or later, where the memory leak issues have been addressed through proper error handling and resource cleanup procedures. System administrators should prioritize patching all affected systems, particularly those handling graphics-intensive workloads or serving as embedded devices with limited memory resources. Additionally, monitoring systems should be implemented to detect unusual memory consumption patterns that might indicate exploitation attempts, though the vulnerability's silent nature makes proactive detection challenging. The fix implemented in the patched kernel versions ensures that all allocated memory segments are properly released regardless of whether kcalloc() or v3d_job_init() operations succeed or fail, thereby preventing the accumulation of leaked memory resources. Organizations should also consider implementing runtime protections such as memory limits and process monitoring to detect and prevent exploitation attempts, while maintaining regular kernel update schedules to address similar vulnerabilities proactively. The vulnerability serves as a reminder of the critical importance of proper error handling in kernel space code, where resource management failures can have cascading effects on system stability and availability.