CVE-2021-47053 in Linux
Summary
by MITRE • 02/28/2024
In the Linux kernel, the following vulnerability has been resolved:
crypto: sun8i-ss - Fix memory leak of pad
It appears there are several failure return paths that don't seem to be free'ing pad. Fix these.
Addresses-Coverity: ("Resource leak")
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Analysis
by VulDB Data Team • 12/09/2024
The vulnerability CVE-2021-47053 represents a critical memory leak issue within the Linux kernel's cryptographic subsystem, specifically affecting the sun8i-ss driver implementation. This flaw resides in the hardware security module responsible for handling cryptographic operations on Allwinner SoC devices, particularly those utilizing the sun8i-ss (Security Subsystem) hardware accelerator. The vulnerability manifests as a resource management failure where allocated memory buffers designated for padding operations are not properly released during error conditions or failure paths within the cryptographic processing pipeline. The issue was identified through static analysis tools that flagged potential resource leaks, specifically categorizing this as a memory leak pattern that could lead to progressive resource exhaustion over time.
The technical implementation flaw occurs within the cryptographic driver's error handling mechanisms where multiple return paths fail to execute proper memory cleanup operations for padding buffers. When cryptographic operations encounter failures during processing, the code branches to various error handling routines that do not consistently invoke memory deallocation functions for the pad buffers that were previously allocated. This pattern violates fundamental resource management principles and creates a persistent memory leak condition that accumulates over time as the system processes additional cryptographic operations. The vulnerability affects the sun8i-ss driver's handling of padding operations during symmetric encryption and decryption processes, where padding is required to align data blocks to cryptographic algorithm requirements.
The operational impact of this memory leak vulnerability extends beyond simple resource consumption, potentially leading to system instability and performance degradation in environments where cryptographic operations are frequently performed. As memory allocated for padding operations accumulates without proper cleanup, the system's available memory pool gradually diminishes, which could result in memory pressure conditions that affect other kernel subsystems or even cause system crashes under sustained load. The vulnerability is particularly concerning in embedded systems and IoT devices that rely heavily on hardware-accelerated cryptographic operations, where memory resources are typically constrained and the impact of resource leaks is amplified. This flaw could be exploited by malicious actors to perform resource exhaustion attacks or could be leveraged as part of a broader attack chain to compromise system availability.
Mitigation strategies for CVE-2021-47053 involve applying the kernel patch that ensures all failure return paths properly release the allocated pad memory buffers before returning from cryptographic operations. The fix implements consistent memory management practices by ensuring that padding buffer deallocation occurs regardless of the execution path taken during error conditions. Security practitioners should prioritize applying the upstream kernel patches released by the Linux kernel development team, which address the specific resource leak in the sun8i-ss driver. Organizations maintaining embedded systems or devices based on Allwinner SoC platforms should conduct thorough testing of the patched kernel versions to ensure compatibility and stability. The vulnerability aligns with CWE-404, which describes improper resource release or unmanaged resources, and may be relevant to ATT&CK technique T1499.004 related to network denial of service through resource exhaustion attacks. Regular monitoring of kernel security updates and proactive vulnerability management practices remain essential for maintaining system security posture against similar memory management flaws.