CVE-2020-7053 in Linux
Summary
by MITRE
In the Linux kernel 4.14 longterm through 4.14.165 and 4.19 longterm through 4.19.96 (and 5.x before 5.2), there is a use-after-free (write) in the i915_ppgtt_close function in drivers/gpu/drm/i915/i915_gem_gtt.c, aka CID-7dc40713618c. This is related to i915_gem_context_destroy_ioctl in drivers/gpu/drm/i915/i915_gem_context.c.
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Analysis
by VulDB Data Team • 03/21/2024
The vulnerability identified as CVE-2020-7053 represents a critical use-after-free condition affecting the Linux kernel's graphics subsystem, specifically within the i915 driver responsible for Intel graphics hardware support. This flaw exists in kernel versions 4.14 longterm through 4.14.165 and 4.19 longterm through 4.19.96, with affected versions extending to 5.x releases before 5.2. The vulnerability manifests as a write operation occurring after memory has been freed, creating a potential exploitation vector that could allow attackers to execute arbitrary code with kernel privileges. The issue is classified as a use-after-free vulnerability under CWE-416, which represents a well-known category of memory safety flaws that have historically led to privilege escalation and system compromise.
The technical implementation of this vulnerability occurs within the i915_ppgtt_close function located in drivers/gpu/drm/i915/i915_gem_gtt.c, where memory management operations become problematic during the cleanup process of graphics memory contexts. The flaw is directly connected to the i915_gem_context_destroy_ioctl function in drivers/gpu/drm/i915/i915_gem_context.c, indicating that the vulnerability is triggered during the destruction of graphics contexts within the Intel graphics driver. When a graphics context is destroyed, the system attempts to free memory resources while simultaneously performing write operations on already freed memory locations, creating a scenario where attackers can manipulate the memory state to achieve unauthorized code execution. This particular flaw demonstrates the complexity of memory management in kernel space graphics drivers where multiple threads and processes interact with shared memory structures.
The operational impact of CVE-2020-7053 extends beyond simple privilege escalation to potentially enable full system compromise, particularly in environments where users have access to graphics functionality through the i915 driver. Attackers could exploit this vulnerability by creating specific graphics contexts and then triggering the context destruction sequence, which would cause the kernel to perform write operations on freed memory. This could result in arbitrary code execution with kernel privileges, allowing attackers to bypass security controls, escalate privileges, and potentially gain complete system control. The vulnerability affects systems running affected kernel versions, including servers, desktops, and embedded systems that utilize Intel graphics hardware, making it a significant concern for enterprise environments and cloud infrastructure providers. According to ATT&CK framework, this vulnerability would map to techniques involving privilege escalation and kernel exploitation, specifically targeting the kernel's memory management subsystem.
Mitigation strategies for CVE-2020-7053 focus primarily on kernel version updates and system hardening measures. The most effective immediate solution involves upgrading to kernel versions that contain the patched implementation, specifically those beyond 4.14.165, 4.19.96, and 5.2 releases where the vulnerability has been addressed. System administrators should also implement monitoring for suspicious graphics context operations and consider disabling unnecessary graphics functionality when not required for system operation. Additional defensive measures include implementing kernel lockdown features, using security modules like SELinux or AppArmor, and maintaining comprehensive system monitoring to detect anomalous behavior that might indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of timely kernel updates and proper memory management practices in kernel space drivers, particularly in graphics subsystems where complex memory management operations are required to support modern graphics functionality.