CVE-2025-38648 in Linux
Summary
by MITRE • 08/22/2025
In the Linux kernel, the following vulnerability has been resolved:
spi: stm32: Check for cfg availability in stm32_spi_probe
The stm32_spi_probe function now includes a check to ensure that the pointer returned by of_device_get_match_data is not NULL before accessing its members. This resolves a warning where a potential NULL pointer dereference could occur when accessing cfg->has_device_mode.
Before accessing the 'has_device_mode' member, we verify that 'cfg' is not NULL. If 'cfg' is NULL, an error message is logged.
This change ensures that the driver does not attempt to access configuration data if it is not available, thus preventing a potential system crash due to a NULL pointer dereference.
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Analysis
by VulDB Data Team • 05/29/2026
The vulnerability identified as CVE-2025-38648 resides within the Linux kernel's spi stm32 driver implementation, specifically addressing a critical null pointer dereference scenario during device probe operations. This issue manifests in the stm32_spi_probe function where the driver attempts to access configuration data without proper validation of the data source. The vulnerability represents a classic software flaw that can lead to system instability and potential denial of service conditions when the device tree configuration data is unavailable or improperly structured.
The technical flaw stems from insufficient input validation within the device probe routine where the function retrieves match data using of_device_get_match_data but fails to verify whether the returned pointer is valid before attempting to dereference it. This pattern directly violates fundamental security principles and coding best practices for defensive programming. When the device tree configuration data cannot be properly parsed or retrieved, the function continues execution without proper error handling, leading to a NULL pointer dereference when accessing the has_device_mode member of the configuration structure. This type of vulnerability falls under the CWE-476 category of NULL Pointer Dereference, which is classified as a high-risk issue in software security assessments.
The operational impact of this vulnerability extends beyond simple system instability to potentially compromise the entire system's reliability and availability. When a null pointer dereference occurs in kernel space, it can result in immediate system crashes, kernel panics, or more subtle issues that may persist and cause intermittent failures. In embedded systems running on stm32 processors, this vulnerability could affect critical infrastructure devices, automotive systems, or industrial control equipment where SPI communication is essential for proper operation. The vulnerability also aligns with ATT&CK technique T1499.004 which involves network disruption through system resource exhaustion or kernel-level crashes, potentially enabling adversaries to perform denial of service attacks against targeted systems.
The mitigation implemented in the patched version addresses the core issue by introducing a null pointer check before accessing the configuration data members. This defensive programming approach ensures that the driver gracefully handles cases where device tree configuration data is unavailable or cannot be properly parsed. The solution follows established security practices by validating all input parameters before use, thereby preventing the potential crash scenario. The error logging mechanism provides visibility into configuration issues while maintaining system stability. This fix aligns with industry standards for kernel security development and represents a fundamental improvement in driver robustness, ensuring that SPI communication subsystems on stm32 platforms operate reliably even when encountering malformed or missing device tree configurations. The resolution demonstrates proper adherence to secure coding practices and helps maintain the integrity of the Linux kernel's device driver framework while preventing potential exploitation scenarios that could lead to system compromise or denial of service conditions.