CVE-2007-3739 in Red Hat
Summary
by MITRE
mm/mmap.c in the hugetlb kernel, when run on PowerPC systems, does not prevent stack expansion from entering into reserved kernel page memory, which allows local users to cause a denial of service (OOPS) via unspecified vectors.
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Analysis
by VulDB Data Team • 07/26/2019
The vulnerability described in CVE-2007-3739 represents a critical flaw in the Linux kernel's memory management subsystem, specifically within the hugetlb implementation on PowerPC architectures. This issue stems from inadequate boundary checking during stack expansion operations, creating a scenario where user-space processes can inadvertently access or corrupt kernel memory regions that should remain protected. The flaw exists in the mm/mmap.c file, which handles memory mapping operations and is fundamental to how the kernel manages virtual memory spaces. When a process attempts to expand its stack, the kernel fails to properly validate whether this expansion would encroach upon reserved kernel page memory areas, leading to potential memory corruption and system instability.
The technical execution of this vulnerability occurs through improper memory management logic that fails to account for the specific memory layout requirements of PowerPC systems. In hugetlb (huge transparent huge pages) configurations, the kernel reserves specific memory regions for kernel operations while allowing user processes to utilize the remainder of the virtual address space. During stack expansion, the kernel's memory management routines do not adequately verify that the expanded stack area does not overlap with these reserved kernel regions. This allows malicious local users to trigger memory access violations that result in kernel panics or OOPS messages, effectively causing a denial of service condition that renders the affected system unstable and potentially unusable.
The operational impact of this vulnerability extends beyond simple denial of service, as it represents a fundamental breakdown in kernel memory protection mechanisms that could potentially be exploited to escalate privileges or gain unauthorized access to kernel memory spaces. The vulnerability affects systems running Linux kernels with hugetlb support on PowerPC hardware platforms, making it particularly concerning for enterprise environments that rely on these architectures for high-performance computing or embedded systems. From a cybersecurity perspective, this vulnerability aligns with CWE-129, which addresses improper validation of input boundaries, and represents a classic example of a memory corruption vulnerability that can lead to privilege escalation or system compromise. The attack vector requires local access to the system, but once exploited, it can result in complete system instability and denial of service conditions.
Mitigation strategies for this vulnerability require immediate kernel updates and patches from the Linux kernel maintainers, as the flaw exists in core memory management functionality that cannot be adequately addressed through configuration changes alone. System administrators should prioritize applying the relevant kernel security patches that address the hugetlb memory management issues in PowerPC implementations. Additionally, monitoring for OOPS messages and system instability patterns can help detect potential exploitation attempts. Organizations should also consider implementing memory protection mechanisms such as stack canaries and address space layout randomization to reduce the effectiveness of potential exploitation attempts. The vulnerability demonstrates the critical importance of proper memory boundary checking in kernel space operations and highlights the need for comprehensive testing of memory management subsystems on specialized hardware platforms like PowerPC architectures. This issue serves as a reminder of the complexity involved in kernel security and the potential for seemingly minor memory management flaws to create significant system stability and security concerns.