CVE-2023-52627 in Linux
Summary
by MITRE • 03/26/2024
In the Linux kernel, the following vulnerability has been resolved:
iio: adc: ad7091r: Allow users to configure device events
AD7091R-5 devices are supported by the ad7091r-5 driver together with the ad7091r-base driver. Those drivers declared iio events for notifying user space when ADC readings fall bellow the thresholds of low limit registers or above the values set in high limit registers. However, to configure iio events and their thresholds, a set of callback functions must be implemented and those were not present until now. The consequence of trying to configure ad7091r-5 events without the proper callback functions was a null pointer dereference in the kernel because the pointers to the callback functions were not set.
Implement event configuration callbacks allowing users to read/write event thresholds and enable/disable event generation.
Since the event spec structs are generic to AD7091R devices, also move those from the ad7091r-5 driver the base driver so they can be reused when support for ad7091r-2/-4/-8 be added.
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Analysis
by VulDB Data Team • 11/04/2024
The vulnerability identified as CVE-2023-52627 affects the Linux kernel's Industrial I/O (IIO) subsystem specifically within the ad7091r driver implementation. This issue impacts AD7091R-5 ADC devices that utilize both the ad7091r-5 driver and the ad7091r-base driver for proper operation. The AD7091R series devices are 12-bit, 8-channel analog-to-digital converters commonly used in industrial applications where precise monitoring of analog signals is required. These devices support event notification mechanisms that alert user-space applications when ADC readings exceed predefined threshold values set in low limit or high limit registers.
The technical flaw stems from the absence of required callback functions necessary for configuring IIO events and their associated threshold parameters. When users attempt to configure events for the ad7091r-5 device through the standard IIO event interface, the kernel experiences a null pointer dereference error. This occurs because the callback function pointers that handle event configuration operations remain uninitialized, leading to kernel memory access violations that can result in system crashes or potential privilege escalation scenarios. The vulnerability represents a classic implementation gap in the IIO subsystem's event handling framework, specifically violating the principle of proper function pointer initialization as outlined in CWE-476.
The operational impact of this vulnerability extends beyond simple system instability to potentially compromise the reliability of industrial monitoring systems that depend on these ADC devices. In production environments where continuous monitoring of analog signals is critical, the inability to properly configure event thresholds can lead to missed alarms or false negatives in system health monitoring. The null pointer dereference represents a kernel-level fault that could be exploited by malicious actors to cause denial of service conditions or potentially gain unauthorized access to system resources. According to ATT&CK framework category T1499, this vulnerability could enable adversaries to disrupt system services through kernel-level memory corruption techniques. The vulnerability affects systems running Linux kernel versions where the ad7091r driver implementation lacks the proper event configuration callbacks, particularly impacting embedded systems and industrial control systems that rely on precise analog signal monitoring.
The resolution implemented addresses the core issue by introducing the missing callback functions that enable proper event configuration operations. These callbacks allow users to read and write event thresholds as well as enable or disable event generation for the ADC device. The fix also includes architectural improvements by moving the generic event specification structures from the ad7091r-5 driver to the base driver, creating a reusable framework that supports future expansion to other AD7091R variants including ad7091r-2, ad7091r-4, and ad7091r-8 devices. This architectural change enhances maintainability and reduces code duplication while ensuring consistent event handling across different device variants. The implementation follows established IIO subsystem patterns and adheres to the kernel's event handling interface specifications, ensuring compatibility with existing user-space applications that depend on the IIO event notification system for real-time monitoring and alerting capabilities. The fix demonstrates proper defensive programming practices by ensuring all required function pointers are properly initialized before being invoked, thereby preventing the null pointer dereference condition that previously occurred during event configuration operations.