CVE-2026-74276

A flaw was found in the Linux kernel's spi: xilinx driver. The driver incorrectly determines the size of its internal buffer, a First-In, First-Out (FIFO) queue. This miscalculation can lead to an overflow when the driver attempts to write more data than the FIFO can hold during a Serial Peripheral Interface (SPI) transaction. This causes the driver to lose data and enter an infinite loop, resulting in a denial of service (DoS) for the system.

A moderate-impact denial-of-service flaw was found in the Linux kernel's Xilinx SPI driver. The driver determines the size of its FIFO by stopping the SPI hardware and writing bytes to the transmit FIFO until the FIFO-full status bit asserts; because the hardware also has a one-byte shift register, the calculated size is one byte larger than the actual FIFO. The same inflated size is then assumed for the receive FIFO. As a result, when an SPI transaction transfers at least the FIFO size in interrupt mode, one received byte is lost (the RX FIFO has one fewer place than the number of bytes shifted out), and the driver's loop that waits for the RX FIFO to become non-empty spins forever, locking the driver. A local user able to perform such an SPI transfer could therefore cause a denial of service; confidentiality and integrity are not affected. Red Hat Product Security rated this flaw Moderate with a CVSS 3.1 score of 5.5 (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). No Red Hat product is affected: all Red Hat Enterprise Linux and Red Hat In-Vehicle OS kernel, kernel-rt, and kernel-ivos-qualcomm records are currently marked not affected because the vulnerable code is not present in the shipped packages.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.