CVE-2026-74415 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
spi: atcspi200: fix use-after-free when driver unbind
DMA resource is initialized after SPI controller registration. So when driver unbind, this can trigger a use-after-free when DMA is torn down while the controller is still alive and triggers DMA transfers.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability in question affects the Linux kernel's spi atcspi200 driver where a use-after-free condition occurs during driver unbinding operations. This issue stems from improper resource initialization ordering within the driver's setup process, creating a temporal gap between when DMA resources are initialized and when the SPI controller is registered with the system.
The technical flaw manifests when the driver unbinds from the SPI controller while DMA resources remain allocated but the controller itself has already been marked as dead or in the process of being torn down. This creates a scenario where the kernel's DMA subsystem attempts to clean up resources that are still referenced by an inactive controller, leading to memory corruption and potential system instability. The root cause lies in the driver initialization sequence where DMA resource allocation occurs after SPI controller registration, creating a window where the controller can be unbound while DMA resources are still active.
The operational impact of this vulnerability extends beyond simple system crashes or hangs as it represents a critical memory safety issue that could potentially be exploited by malicious actors. When the driver unbinds, the kernel's DMA subsystem may attempt to access freed memory locations, leading to unpredictable behavior including kernel oops, system panics, or more concerning denial-of-service conditions. This vulnerability affects systems using the atcspi200 SPI controller implementation and could compromise system integrity during normal operation or under specific stress conditions.
This issue aligns with CWE-416 which describes use-after-free vulnerabilities where memory is accessed after it has been freed, and represents a classic case of improper resource management in kernel space. The vulnerability may also map to ATT&CK technique T1068 which involves exploiting local privilege escalation opportunities through kernel vulnerabilities, though the primary impact here is system stability rather than direct privilege escalation. Mitigation strategies should focus on ensuring proper resource ordering during driver initialization and implementing defensive programming practices that prevent access to freed resources.
The fix for this vulnerability requires modifying the driver's initialization sequence to ensure DMA resources are properly initialized before SPI controller registration, or implementing proper synchronization mechanisms that prevent unbinding operations while DMA transfers may still be in progress. Additionally, proper reference counting and resource lifecycle management should be enforced to ensure that DMA cleanup only occurs after all potential references to those resources have been resolved. System administrators should update their kernel versions to include the patched driver implementation and monitor for any unusual system behavior or stability issues related to SPI controller operations.
The vulnerability demonstrates the complexity of kernel-level programming where timing issues and resource management can create subtle but critical security problems. It underscores the importance of proper ordering in device driver initialization and the need for comprehensive testing of driver unbinding scenarios, particularly in systems with complex resource dependencies like DMA controllers and SPI buses. This particular issue represents a failure in defensive programming practices that should have been caught during code review or automated testing phases of development.
The corrected implementation should ensure that when a driver unbinds from a controller, all associated resources including DMA memory mappings are properly released before the controller structure itself is freed. The kernel's device model and resource management subsystems provide mechanisms to handle such scenarios properly, but the atcspi200 driver failed to utilize these correctly in its initialization sequence, creating an exploitable window where system memory could be accessed after deallocation. This type of vulnerability highlights the critical nature of kernel development where even seemingly minor ordering issues can create significant security and stability concerns for entire systems relying on SPI communication protocols.