CVE-2026-64170 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
spi: qup: fix error pointer deref after DMA setup failure
The driver falls back to PIO mode if DMA setup fails during probe.
Make sure to the clear the DMA channel pointers on setup failure to avoid dereferencing an error pointer (or attempting to release a channel a second time) on later probe errors or driver unbind.
This issue was flagged by Sashiko when reviewing a devres allocation conversion patch.
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Analysis
by VulDB Data Team • 07/20/2026
The vulnerability in question affects the Linux kernel's spi qup driver implementation, specifically addressing a critical error pointer dereference scenario that can occur during device initialization. This flaw represents a classic software defect where improper resource management leads to potential system instability and security implications. The issue manifests when the driver attempts to fall back from DMA mode to PIO mode upon DMA setup failure, but fails to properly clear the DMA channel pointers. Such oversight creates a dangerous condition where subsequent error handling paths may attempt to dereference invalid pointers or release already-freed resources, potentially leading to kernel panics or arbitrary code execution.
The technical root cause of this vulnerability lies in improper resource cleanup during error handling pathways within the driver's probe function. When DMA setup fails, the driver correctly identifies the need to fall back to PIO mode as a graceful degradation mechanism, but the implementation contains a critical oversight in pointer management. The DMA channel pointers remain in an invalid state after the initial failure, creating a scenario where later code paths that expect valid pointers will encounter error values instead of proper resource handles. This type of defect aligns with CWE-476 which specifically addresses null pointer dereference conditions, though in this case it involves error pointer handling rather than simple null references. The vulnerability demonstrates poor defensive programming practices where error recovery paths do not properly clean up state before proceeding to alternative execution branches.
The operational impact of this vulnerability extends beyond simple system crashes to potentially enable more serious security consequences within kernel space operations. When drivers fail to properly manage their resource lifecycles, especially in error conditions, they create opportunities for attackers to exploit these gaps through carefully crafted inputs or environmental conditions that trigger the problematic code paths. The vulnerability affects systems utilizing the spi qup driver, which is commonly found in embedded systems and mobile devices where SPI communication is essential for peripheral device control. The potential for double-free conditions or use-after-free scenarios makes this particularly concerning from a security perspective, as these types of bugs can be exploited to escalate privileges or gain unauthorized access to system resources. According to ATT&CK framework category T1068, this vulnerability could potentially enable privilege escalation if exploited successfully.
The recommended mitigation strategies focus on implementing proper error handling and resource cleanup procedures within the driver's probe function. The fix requires ensuring that DMA channel pointers are explicitly cleared or reset when DMA setup fails, preventing subsequent code paths from attempting to dereference invalid handles. This approach aligns with best practices for kernel development and follows the principle of defensive programming where all resources must be properly managed regardless of execution path taken. Additionally, comprehensive testing should include scenarios that specifically trigger DMA failures during probe operations to verify that the fallback mechanisms work correctly without leaving stale pointers in memory. The fix also emphasizes the importance of proper devres allocation handling as highlighted by the initial code review that identified this issue, reinforcing the need for careful attention to resource management during kernel development and patch review processes.