CVE-2024-42279 in Linux
Summary
by MITRE • 08/17/2024
In the Linux kernel, the following vulnerability has been resolved:
spi: microchip-core: ensure TX and RX FIFOs are empty at start of a transfer
While transmitting with rx_len == 0, the RX FIFO is not going to be emptied in the interrupt handler. A subsequent transfer could then read crap from the previous transfer out of the RX FIFO into the start RX buffer. The core provides a register that will empty the RX and TX FIFOs, so do that before each transfer.
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Analysis
by VulDB Data Team • 02/01/2026
The vulnerability identified as CVE-2024-42279 resides within the Linux kernel's SPI subsystem, specifically affecting the microchip-core driver implementation. This flaw represents a classic buffer contamination issue that can compromise data integrity during serial peripheral interface communications. The vulnerability manifests when the SPI driver handles transfers where the receive length is set to zero, creating a scenario where the receive FIFO remains uncleared between successive data transfers. The root cause lies in the driver's failure to properly initialize the FIFO state before initiating new transfers, leaving residual data in the receive buffer that can be misinterpreted as valid incoming data from subsequent operations.
The technical implementation flaw stems from the absence of proper FIFO state management within the SPI transfer initiation sequence. When a transfer is configured with rx_len == 0, the interrupt handler does not execute the necessary cleanup routine to empty the receive FIFO, which is a critical oversight in the driver's design. This behavior creates a data contamination pathway where stale data from previous transfers can persist in the FIFO buffers and subsequently be read into the current transfer's receive buffer. The microchip-core driver provides a dedicated hardware register specifically designed to clear both transmit and receive FIFOs, but this register is not being utilized at the beginning of each transfer operation, creating the exploitable condition.
The operational impact of this vulnerability extends beyond simple data corruption, potentially enabling malicious actors to manipulate or extract sensitive information from SPI communications. Attackers could exploit this weakness to inject false data into SPI transactions, potentially compromising the integrity of critical system communications, especially in embedded systems where SPI interfaces are used for security-sensitive operations. The vulnerability affects any system utilizing the microchip-core SPI driver implementation and could be particularly concerning in industrial control systems, automotive applications, or IoT devices where SPI interfaces handle critical data flows. The flaw demonstrates a failure in the driver's state management and initialization protocols, which aligns with CWE-665 improper initialization of a resource, specifically in the context of hardware FIFO management.
This vulnerability can be addressed through proper implementation of the hardware FIFO clearing register before each SPI transfer operation, ensuring that both TX and RX FIFOs are emptied at transfer initiation. The mitigation strategy involves modifying the driver code to include the FIFO clearing operation as part of the standard transfer setup routine, which aligns with the principle of least privilege and proper resource initialization. Security practitioners should implement kernel updates that include this fix, as it represents a straightforward hardware abstraction layer correction. The fix demonstrates the importance of comprehensive FIFO management in embedded systems and aligns with ATT&CK technique T1070.004 for indicator removal through manipulation of system components. The vulnerability underscores the critical need for proper hardware resource state management in kernel drivers and highlights the potential for seemingly minor implementation oversights to create significant security risks in embedded systems environments where SPI communication is prevalent.