CVE-2020-29370 in Linux
Summary
by MITRE • 11/28/2020
An issue was discovered in kmem_cache_alloc_bulk in mm/slub.c in the Linux kernel before 5.5.11. The slowpath lacks the required TID increment, aka CID-fd4d9c7d0c71.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 12/11/2020
The vulnerability identified as CVE-2020-29370 resides within the Linux kernel's memory management subsystem, specifically in the slub allocator implementation located in mm/slub.c. This flaw affects versions prior to 5.5.11 and represents a critical issue in the kernel's memory allocation mechanisms that could potentially lead to system instability or security implications. The vulnerability manifests in the kmem_cache_alloc_bulk function, which is responsible for allocating multiple objects from a kernel memory cache in a single operation. The issue stems from an insufficient TID (Transaction ID) increment mechanism within the slowpath execution flow of this memory allocation function.
The technical root cause of this vulnerability lies in the improper handling of transaction identifiers during memory allocation operations. When the slub allocator processes bulk memory allocations, it follows different execution paths depending on system conditions and allocation requirements. The slowpath, which handles more complex allocation scenarios, fails to properly increment the TID counter that is essential for maintaining consistency and tracking allocation transactions. This TID increment is crucial for maintaining the integrity of the memory management subsystem and ensuring proper synchronization between concurrent allocation operations.
The operational impact of this vulnerability extends beyond simple memory allocation failures, potentially affecting system stability and security posture. In environments where high-frequency memory allocation operations occur, particularly in kernel modules or system services that rely heavily on dynamic memory management, this flaw could lead to memory corruption or inconsistent allocation states. The missing TID increment creates opportunities for race conditions and memory management inconsistencies that could be exploited by malicious actors to cause system crashes or potentially escalate privileges. The vulnerability is particularly concerning in systems where kernel memory management is heavily utilized, as it could provide attackers with a pathway to destabilize critical system operations or gain unauthorized access to system resources.
From a cybersecurity perspective, this vulnerability aligns with CWE-119, which addresses memory corruption issues, and represents a potential entry point for attacks following the MITRE ATT&CK framework's privilege escalation tactics. The flaw could be leveraged in conjunction with other kernel vulnerabilities to achieve more significant security breaches. Organizations should prioritize patching affected systems to address this vulnerability, as the Linux kernel maintainers have released fixes in version 5.5.11 and subsequent releases. The remediation process involves updating the kernel to a patched version that properly implements the TID increment mechanism in the slub allocator's slowpath, ensuring that memory allocation operations maintain proper transaction tracking and system stability. System administrators should also monitor for any unusual system behavior or crashes that might indicate exploitation attempts, as the vulnerability could be used to create denial-of-service conditions or facilitate more sophisticated attacks against kernel-level security controls.