CVE-2026-93825 in Linux
Summary
by MITRE • 09/24/2026
In the Linux kernel, the following vulnerability has been resolved:
spi: Add NULL check for spi_get_device_id() in spi_get_device_match_data()
Prevent NULL pointer dereference when spi_get_device_id() returns NULL, which can happen when using driver_override without matching SPI ID entry.
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Analysis
by VulDB Data Team • 09/24/2026
The Linux kernel's Serial Peripheral Interface subsystem contains a logic flaw within the function responsible for retrieving device match data during driver initialization or probe operations. Specifically, the implementation of spi_get_device_match_data fails to validate the return value from the helper function spi_get_device_id before attempting to access it as part of subsequent matching logic. This oversight creates a scenario where an invalid memory address is dereferenced if the underlying identifier lookup yields no result. In standard operation, this function is expected to locate specific hardware identifiers associated with supported SPI devices, but under certain configuration conditions, particularly when driver overrides are utilized without corresponding ID table entries, the system returns a null pointer instead of valid data structures.
This vulnerability manifests primarily in environments where kernel developers or administrators employ the driver_override mechanism to force a specific driver onto an SPI device that does not natively match any entry in the driver's supported ID list. When such a mismatch occurs and spi_get_device_id is invoked, it returns NULL because no matching identifier exists within the defined tables. The calling function proceeds without checking for this null condition, leading directly to a kernel panic or system crash due to an invalid memory access. This represents a classic denial of service vector where local privilege escalation may also be possible if the attacker can trigger specific code paths that leverage this dereference for arbitrary write operations, although the primary impact observed is typically system instability and unavailability.
From a technical classification perspective, this flaw aligns with CWE-476, which denotes NULL Pointer Dereference vulnerabilities. These errors occur when software attempts to use a pointer variable that has not been initialized or has been set to null, leading to unpredictable behavior depending on the memory layout at runtime. In the context of kernel development, such bugs are particularly severe because they compromise the stability and integrity of the entire operating system rather than just an isolated application process. The lack of defensive programming practices in handling return values from internal API calls is a common source of these defects in large codebases like the Linux kernel.
The operational impact includes immediate service disruption for systems relying on SPI peripherals when specific override configurations are applied incorrectly or unexpectedly. For embedded devices, IoT hardware, and industrial control systems that depend heavily on stable SPI communication with sensors, actuators, or memory chips, this vulnerability can lead to complete system failure during boot sequences or runtime reconfiguration events. Attackers who have the ability to modify kernel parameters or load modules could potentially exploit this condition to cause a denial of service against critical infrastructure components managed by Linux-based controllers.
Mitigation strategies involve applying the upstream patch that introduces explicit null checks within spi_get_device_match_data before any dereferencing operations occur. System administrators should ensure their kernels are updated with the latest stable releases containing this fix, as it is already resolved in mainline versions. For organizations unable to update immediately due to certification or stability constraints, disabling driver_override capabilities for SPI devices where possible can reduce exposure until patches are deployed. Additionally, rigorous code review processes that mandate validation of all pointer returns from internal kernel functions should be enforced to prevent similar defects in future development cycles.
This incident highlights the importance of robust error handling in low-level system software and reinforces adherence to secure coding standards such as those outlined by CERT C or MISRA guidelines regarding pointer safety. The ATT&CK framework categorizes this type of exploitation under techniques involving kernel vulnerabilities, specifically noting how local attackers can leverage memory corruption bugs for privilege escalation or denial of service. Continuous monitoring and automated static analysis tools that detect null dereference patterns are essential components of a comprehensive defense-in-depth strategy against such kernel-level flaws.