CVE-2023-52802 in Linux
Summary
by MITRE • 05/21/2024
In the Linux kernel, the following vulnerability has been resolved:
iio: adc: stm32-adc: harden against NULL pointer deref in stm32_adc_probe()
of_match_device() may fail and returns a NULL pointer.
In practice there is no known reasonable way to trigger this, but in case one is added in future, harden the code by adding the check
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Analysis
by VulDB Data Team • 06/08/2024
The vulnerability under discussion represents a potential null pointer dereference condition within the stm32-adc driver of the Linux kernel's industrial I/O subsystem. This issue manifests specifically during the probe phase of device initialization when the stm32_adc_probe() function attempts to process device match data. The root cause stems from the of_match_device() function which can return a NULL pointer under certain conditions, particularly when device tree matching fails or encounters unexpected configurations. While this vulnerability appears to have no known practical exploitation vectors at present, it represents a defensive coding weakness that could become exploitable if future code modifications introduce new failure paths.
The technical flaw resides in the absence of proper null pointer validation following the call to of_match_device() within the stm32_adc_probe() function. This pattern violates fundamental defensive programming principles and creates a potential crash scenario where subsequent operations attempt to dereference a NULL pointer. The vulnerability directly relates to CWE-476 which defines null pointer dereference as a common weakness in software systems. When the device tree matching process fails, the function returns NULL instead of a valid match structure, but the code does not check for this condition before proceeding with operations that assume a valid pointer exists.
The operational impact of this vulnerability primarily manifests as system instability through kernel panic conditions or device driver failures. When the null pointer dereference occurs during probe execution, it can cause the entire kernel subsystem to become unresponsive or require manual intervention to recover. This is particularly concerning in embedded systems where the stm32-adc driver handles critical analog-to-digital conversion functions for industrial control applications. The vulnerability affects any system utilizing the STM32 ADC driver with device tree configuration, potentially leading to complete system crashes or service interruptions in production environments.
Mitigation strategies for this vulnerability focus on implementing defensive programming practices within the kernel codebase. The recommended approach involves adding explicit null pointer checks immediately after the of_match_device() call before proceeding with any operations that depend on the returned match structure. This remediation aligns with ATT&CK technique T1547.006 which addresses kernel-level persistence mechanisms and emphasizes the importance of input validation in system drivers. Additionally, implementing proper error handling and logging mechanisms can help detect potential exploitation attempts or misconfigurations that might lead to this condition. The fix should follow established kernel development practices for device driver initialization and ensure all pointer operations include appropriate validation checks to prevent similar issues across other subsystems.
The resolution of this vulnerability demonstrates the importance of proactive security measures in kernel development, particularly in embedded systems where device drivers handle critical hardware interfaces. This type of defensive coding improves overall system resilience and reduces attack surface exposure while maintaining operational stability. The fix serves as a model for other kernel subsystems to implement similar null pointer validation checks during device initialization phases, thereby strengthening the entire Linux kernel security posture against potential future exploitation vectors.