CVE-2021-47052 in Linux
Summary
by MITRE • 02/28/2024
In the Linux kernel, the following vulnerability has been resolved:
crypto: sa2ul - Fix memory leak of rxd
There are two error return paths that are not freeing rxd and causing memory leaks. Fix these.
Addresses-Coverity: ("Resource leak")
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Analysis
by VulDB Data Team • 12/09/2024
The vulnerability identified as CVE-2021-47052 represents a critical memory management flaw within the Linux kernel's cryptographic subsystem, specifically affecting the sa2ul driver component. This issue manifests as a resource leak that occurs during error handling scenarios within the cryptographic processing pipeline. The sa2ul driver is responsible for handling cryptographic operations in certain hardware implementations, and the memory leak affects the rxd (receive descriptor) structures that are essential for proper data handling during cryptographic transactions.
The technical flaw stems from improper error handling within the driver's code implementation where two distinct error return paths fail to properly release allocated rxd structures. This memory leak occurs when the driver encounters exceptional conditions during cryptographic processing operations, causing the system to retain memory that should be freed and returned to the available pool. The vulnerability is classified as a resource leak under the Coverity static analysis framework, indicating that the issue was identified through automated code analysis rather than through runtime exploitation.
The operational impact of this vulnerability extends beyond simple memory consumption issues, as persistent memory leaks can lead to progressive system degradation and potential denial of service conditions. When the sa2ul driver encounters error conditions during cryptographic operations, the leaked memory accumulates over time, eventually consuming significant portions of available system resources. This can result in reduced system performance, application instability, or complete system crashes when memory exhaustion occurs, particularly in environments with high cryptographic transaction volumes or continuous cryptographic processing demands.
Mitigation strategies for CVE-2021-47052 focus primarily on applying the kernel patch that corrects the memory leak by ensuring proper cleanup of rxd structures in all error return paths. System administrators should prioritize updating their Linux kernel installations to versions containing the fix, typically found in kernel releases 5.13 and later. The fix aligns with common security best practices for resource management and follows established patterns for error handling in kernel space code. Additionally, monitoring systems for memory usage patterns and implementing automated alerting for unusual memory consumption can help detect potential exploitation of this vulnerability before it causes significant operational impact.
This vulnerability demonstrates the critical importance of proper resource management in kernel-level code and highlights how seemingly minor error handling oversights can lead to significant security implications. The issue relates to CWE-401, which specifically addresses memory leaks in software systems, and could potentially be leveraged by attackers to perform resource exhaustion attacks. The fix represents a standard defensive programming practice that ensures proper cleanup of allocated resources regardless of execution flow, aligning with the ATT&CK framework's emphasis on maintaining system integrity through proper resource management and error handling mechanisms.