CVE-2022-49569 is a vulnerability identified in the Linux kernel specifically affecting the bcm2835 SPI (Serial Peripheral Interface) driver. The issue arises in the bcm2835_spi_handle_err() function, which is invoked when an IRQ (interrupt request) based SPI transfer times out. Due to a prior commit (1513ceee70f2) that dropped the dma_pending flag unconditionally, the driver cancels both TX (transmit) and RX (receive) DMA (Direct Memory Access) transfers without verifying if the corresponding DMA pointers (ctlr->dma_tx and ctlr->dma_rx) are valid. This leads to a NULL pointer dereference when these pointers are accessed while being unset, causing a kernel crash or system instability. The vulnerability is a classic example of improper pointer validation after a code change affecting DMA transfer handling. The fix involves adding checks to ensure that ctlr->dma_tx and ctlr->dma_rx pointers are valid before dereferencing them, preventing the NULL pointer dereference and associated kernel panic. This vulnerability is specific to the bcm2835 SPI controller driver, which is commonly used in certain embedded Linux systems and single-board computers, such as Raspberry Pi devices. There is no evidence of known exploits in the wild, and no CVSS score has been assigned yet. The vulnerability was published on February 26, 2025.

The primary impact of CVE-2022-49569 is a potential denial of service (DoS) condition caused by a kernel crash due to NULL pointer dereference in the bcm2835 SPI driver. For European organizations using Linux systems with bcm2835 SPI hardware—commonly found in embedded devices, IoT gateways, and industrial control systems—this vulnerability could lead to unexpected system reboots or failures, disrupting critical operations. While the vulnerability does not directly lead to privilege escalation or remote code execution, the resulting instability can affect availability and reliability of devices. In sectors such as manufacturing, energy, and telecommunications where embedded Linux devices are prevalent, this could cause operational interruptions. Additionally, if exploited in a targeted manner, attackers could induce repeated crashes to degrade service or cause safety concerns in industrial environments. However, the scope is limited to systems using the bcm2835 SPI controller, which narrows the affected population. Since no known exploits exist, the immediate risk is moderate but could increase if exploit code emerges.

To mitigate CVE-2022-49569, organizations should: 1) Apply the official Linux kernel patches that include the fix for this vulnerability as soon as they become available, ensuring that the bcm2835 SPI driver properly validates DMA pointers before dereferencing. 2) Identify and inventory all devices running Linux kernels with bcm2835 SPI drivers, especially embedded and IoT devices, to assess exposure. 3) For devices where patching the kernel is not immediately feasible, consider isolating or segmenting affected devices within the network to limit potential impact from crashes or induced DoS conditions. 4) Monitor system logs for kernel panics or SPI-related errors that could indicate attempts to trigger this vulnerability. 5) Engage with device vendors to confirm firmware or kernel updates that address this issue, particularly for embedded platforms. 6) Implement robust backup and recovery procedures for critical embedded systems to minimize downtime in case of crashes. These steps go beyond generic advice by focusing on embedded device management, patch prioritization, and operational continuity.