CVE-2021-47150 in Linux
Summary
by MITRE • 03/25/2024
In the Linux kernel, the following vulnerability has been resolved:
net: fec: fix the potential memory leak in fec_enet_init()
If the memory allocated for cbd_base is failed, it should free the memory allocated for the queues, otherwise it causes memory leak.
And if the memory allocated for the queues is failed, it can return error directly.
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Analysis
by VulDB Data Team • 08/04/2025
The vulnerability identified as CVE-2021-47150 represents a critical memory management flaw within the Linux kernel's Freescale Enhanced Ethernet Controller (FEC) driver implementation. This issue specifically affects the fec_enet_init() function which is responsible for initializing the FEC network interface. The vulnerability manifests as a potential memory leak that occurs during the driver initialization process when memory allocation fails for critical data structures. The flaw demonstrates poor error handling practices where the kernel fails to properly clean up previously allocated memory resources when subsequent allocation attempts encounter failures, creating a resource exhaustion scenario that could impact system stability and performance.
The technical implementation of this vulnerability stems from inadequate memory management within the FEC driver's initialization routine. When the driver attempts to allocate memory for the cbd_base structure and subsequent queue allocations, proper error handling mechanisms are absent or insufficient. According to CWE-401, this represents a classic memory leak condition where allocated memory is not properly released when allocation failures occur. The driver should implement proper resource cleanup protocols to ensure that any partially allocated memory is freed when subsequent allocation attempts fail, preventing the accumulation of unreleased memory blocks that could eventually lead to system resource exhaustion.
The operational impact of this vulnerability extends beyond simple memory consumption issues to potentially compromise system reliability and availability. In embedded systems or network appliances that rely heavily on FEC drivers for network operations, this memory leak could gradually consume available system memory, leading to performance degradation, system instability, or even complete system crashes. The vulnerability affects systems running Linux kernel versions where the FEC driver is utilized, particularly those implementing Freescale i.MX series processors and similar embedded networking solutions. This type of memory leak vulnerability aligns with ATT&CK technique T1490, which covers resource exhaustion attacks that can be exploited to deny service or compromise system stability through memory consumption.
Mitigation strategies for CVE-2021-47150 should focus on implementing comprehensive error handling and resource cleanup procedures within the FEC driver initialization code. System administrators should prioritize updating to kernel versions that contain the patched implementation, where proper memory cleanup routines have been implemented to ensure that all allocated resources are freed when allocation failures occur. The fix should enforce a robust cleanup mechanism that releases previously allocated memory for cbd_base and queue structures when subsequent allocations fail, preventing the accumulation of leaked memory blocks. Additionally, system monitoring should include memory usage tracking to detect potential memory leak accumulation patterns that could indicate the presence of this vulnerability in unpatched systems. Regular kernel updates and security patch management processes are essential to prevent exploitation of this memory management flaw that could be leveraged by attackers to perform resource exhaustion attacks against networked systems.