CVE-2023-52749 is a vulnerability identified in the Linux kernel's SPI (Serial Peripheral Interface) subsystem. The issue arises from a race condition during system suspend and resume operations involving synchronous SPI transfers that use the noqueue mechanism. Specifically, when a synchronous SPI transfer is active during system suspend, the kernel fails to properly wait for the transfer to complete before suspending. Upon system resume, the spi_controller_resume() function resets the current message pointer (cur_msg) to NULL, but the SPI transfer context resumes and calls spi_finalize_current_message(), which attempts to dereference this now NULL pointer. This results in a null pointer dereference exception, causing a kernel crash or system instability. The root cause is the lack of synchronization between the suspend/resume sequence and ongoing SPI transfers. The fix involves acquiring the bus mutex and setting/checking a suspend flag to ensure synchronous transfers complete before suspend proceeds, preventing the race condition and null pointer dereference. This vulnerability affects Linux kernel versions identified by the commit hashes provided, and it is relevant to systems using SPI devices with synchronous transfers during suspend/resume cycles. No known exploits are reported in the wild as of the publication date.

For European organizations, this vulnerability can lead to system crashes or kernel panics on Linux-based devices that utilize SPI peripherals, particularly embedded systems, industrial controllers, IoT devices, and certain servers or workstations that rely on SPI-connected hardware. The impact includes potential denial of service (DoS) conditions due to unexpected system reboots or freezes during suspend/resume cycles. This can disrupt critical operations, especially in industrial automation, telecommunications, and infrastructure sectors where Linux is prevalent. While the vulnerability does not directly lead to privilege escalation or data leakage, the availability impact can be significant in environments requiring high uptime and reliability. Additionally, repeated crashes could cause hardware wear or data corruption in dependent systems. The absence of known exploits reduces immediate risk, but the vulnerability should be addressed proactively to maintain operational stability and security compliance.

European organizations should apply the official Linux kernel patches that address CVE-2023-52749 as soon as they become available from their Linux distribution vendors or directly from the Linux kernel source. Until patched, organizations should audit and identify systems using SPI devices with synchronous transfers, especially those that undergo frequent suspend/resume cycles. Where feasible, disable suspend/resume functionality on critical systems or avoid using synchronous SPI transfers during suspend operations. Implement monitoring to detect kernel crashes or unexpected reboots related to SPI activity. For embedded and IoT devices, coordinate with hardware vendors to ensure firmware updates incorporate the fix. Additionally, review and enhance system suspend/resume procedures to ensure proper synchronization with hardware communication protocols. Employ kernel debugging and logging to trace SPI transfer states during suspend/resume to detect anomalies early.