CVE-2016-10764 in Linux
Summary
by MITRE • 01/25/2023
In the Linux kernel before 4.9.6, there is an off by one in the drivers/mtd/spi-nor/cadence-quadspi.c cqspi_setup_flash() function. There are CQSPI_MAX_CHIPSELECT elements in the ->f_pdata array so the ">" should be ">=" instead.
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Analysis
by VulDB Data Team • 11/13/2023
The vulnerability identified as CVE-2016-10764 represents a critical buffer overflow condition within the Linux kernel's SPI NOR flash driver implementation. This flaw exists specifically in the cadence-quadspi.c file where the cqspi_setup_flash() function handles flash chip initialization. The issue stems from an incorrect boundary condition in array indexing that can lead to unauthorized memory access patterns and potential system compromise. The affected kernel versions prior to 4.9.6 contain this programming error that affects the management of multiple chip select lines for SPI flash devices.
The technical root cause of this vulnerability manifests as an off-by-one error in the conditional logic governing array traversal. The function processes a fixed-size array ->f_pdata containing CQSPI_MAX_CHIPSELECT elements, yet the comparison operation uses a strict greater-than operator instead of a greater-than-or-equal operator. This subtle programming mistake allows the code to attempt accessing memory beyond the allocated array boundaries when the index equals the maximum allowed value. Such buffer overflows can result in memory corruption, data leakage, or execution of arbitrary code within kernel space.
The operational impact of this vulnerability extends beyond simple memory corruption to potentially enable privilege escalation attacks within the kernel environment. When exploited, this flaw could allow malicious actors to gain elevated privileges and execute arbitrary code with kernel-level permissions. The vulnerability affects systems utilizing Cadence Quad SPI controllers for managing SPI NOR flash memory devices, which are commonly found in embedded systems, network equipment, and various IoT devices. Attackers could leverage this weakness to compromise system integrity, potentially leading to complete system takeover or persistent backdoor installation.
This vulnerability aligns with CWE-129, which specifically addresses improper validation of array index values, and demonstrates characteristics consistent with ATT&CK technique T1068, which involves exploitation of vulnerabilities to gain system privileges. The flaw represents a classic case of insufficient boundary checking in kernel drivers, where the lack of proper input validation creates opportunities for attackers to manipulate memory layouts. Organizations running affected kernel versions should prioritize patching to prevent exploitation, as the vulnerability exists in the core kernel functionality that manages hardware device communication and memory access controls.
Mitigation strategies should include immediate kernel updates to version 4.9.6 or later where the fix has been implemented. The patch corrects the comparison operator from ">" to ">=" ensuring proper bounds checking for the chip select array access. Additionally, system administrators should implement monitoring for unusual memory access patterns and consider deploying kernel hardening techniques such as stack canaries and address space layout randomization. Regular security audits of kernel modules and driver implementations should be conducted to identify similar boundary condition issues that could present similar risks to system stability and security.