CVE-2019-19065 in Linux
Summary
by MITRE
A memory leak in the sdma_init() function in drivers/infiniband/hw/hfi1/sdma.c in the Linux kernel before 5.3.9 allows attackers to cause a denial of service (memory consumption) by triggering rhashtable_init() failures, aka CID-34b3be18a04e. NOTE: This has been disputed as not a vulnerability because "rhashtable_init() can only fail if it is passed invalid values in the second parameter's struct, but when invoked from sdma_init() that is a pointer to a static const struct, so an attacker could only trigger failure if they could corrupt kernel memory (in which case a small memory leak is not a significant problem).
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Analysis
by VulDB Data Team • 08/05/2024
The vulnerability identified as CVE-2019-19065 resides within the Linux kernel's InfiniBand hardware driver implementation, specifically in the sdma_init() function located in drivers/infiniband/hw/hfi1/sdma.c. This memory leak occurs during the initialization process of the SDMA (System DMA) engine which handles data movement operations for high-performance computing networks. The flaw manifests when rhashtable_init() function fails during the initialization sequence, leading to improper memory cleanup and subsequent memory consumption that can accumulate over time. The vulnerability affects Linux kernel versions prior to 5.3.9, making it a significant concern for systems running older kernel versions that are commonly found in enterprise environments and high-performance computing clusters where InfiniBand networking is prevalent.
The technical implementation of this vulnerability stems from the memory management practices within the sdma_init() function where the rhashtable_init() call can fail under specific conditions, but the subsequent error handling does not properly release allocated memory resources. According to CWE-401, this represents a classic memory leak vulnerability where allocated memory is not properly deallocated, leading to gradual memory exhaustion. The rhashtable_init() function is designed to initialize hash tables for efficient data lookup operations, but when it fails due to improper parameter validation or memory corruption, the sdma_init() function fails to clean up its allocated resources. This failure pattern creates a situation where each invocation of the problematic code path results in a small but persistent memory leak that can compound over time.
From an operational perspective, this vulnerability presents a significant denial of service risk for systems utilizing InfiniBand hardware accelerators. An attacker who can trigger the rhashtable_init() failure condition could repeatedly invoke the problematic code path, leading to progressive memory consumption that eventually depletes available system resources. The impact extends beyond simple resource exhaustion as it affects system stability and performance, potentially causing applications to crash or become unresponsive. Systems running kernel versions before 5.3.9 are particularly vulnerable since they lack the memory leak fixes that were implemented in later kernel releases. The vulnerability is especially concerning in high-availability environments where maintaining system uptime and performance is critical, as even small memory leaks can accumulate to cause significant service disruption.
The disputed nature of this vulnerability stems from the argument that rhashtable_init() can only fail when passed invalid parameters, and in the specific context of sdma_init() the parameters are a pointer to a static const struct, making it extremely difficult for an attacker to trigger the failure condition without first achieving kernel memory corruption. However, this analysis overlooks the potential for indirect exploitation pathways through other kernel vulnerabilities or through complex attack scenarios that might manipulate memory state. The ATT&CK framework categorizes this as a resource exhaustion technique under T1499, where adversaries consume system resources to prevent normal operations. While the direct exploitability may be limited, the vulnerability remains a legitimate concern for systems that might be exposed to multiple attack vectors or for environments where memory management issues could compound. The kernel developers' response indicates that the vulnerability was not considered significant given the attack surface requirements, but security practitioners should still consider the potential for escalation through related vulnerabilities or in combination with other exploits.
Mitigation strategies for this vulnerability include upgrading to Linux kernel version 5.3.9 or later where the memory leak has been addressed through proper error handling and resource cleanup in the sdma_init() function. Organizations should prioritize kernel updates as part of their regular security maintenance procedures, particularly for systems running InfiniBand hardware where this vulnerability could be exploited. Additionally, system administrators should monitor memory consumption patterns on affected systems to detect potential exploitation attempts, though the vulnerability's limited exploitability means such monitoring should be part of broader system health assessments rather than specific alerting for this particular issue. The fix implemented in the kernel ensures that even when rhashtable_init() fails, all allocated resources are properly cleaned up, preventing the accumulation of memory leaks that could lead to denial of service conditions.