CVE-2023-52488 is a vulnerability identified in the Linux kernel's serial driver for the SC16IS7XX integrated circuit (IC), which is used for serial communication over SPI or I2C buses. The SC16IS7XX IC supports a burst mode for FIFO (First In, First Out) buffer access, where the initial register address is sent once, followed by multiple data bytes without incrementing the register address for each byte. The Linux kernel previously used regmap_raw_read() and regmap_raw_write() functions to perform multi-byte I/O operations on the FIFO registers. These functions assume that the register address increments after each byte, which is not the case in burst mode for this IC. This mismatch caused corruption of the regmap cache because the cache management logic incorrectly handled the non-incrementing register addresses. To work around this, manual cache control was implemented, but it was error-prone and inefficient. The vulnerability was resolved by converting the FIFO read/write functions to use regmap_noinc versions, which correctly handle non-incrementing register addresses, and by declaring FIFO registers as volatile to prevent caching. This fix eliminates the risk of regmap cache corruption during FIFO accesses, ensuring data integrity and stable operation of the serial driver. No known exploits are reported in the wild, and the vulnerability is specific to the Linux kernel's handling of the SC16IS7XX serial driver FIFO burst mode accesses.

The vulnerability primarily affects the integrity and reliability of data transfers through the SC16IS7XX serial interface on Linux systems. If exploited or triggered inadvertently, regmap cache corruption could lead to incorrect data being read from or written to the FIFO buffers, potentially causing device malfunctions, data corruption, or system instability. For European organizations, especially those relying on embedded Linux systems or industrial control systems using SC16IS7XX-based serial communication, this could disrupt critical operations or lead to erroneous sensor or actuator data. Although no active exploits are known, the flaw could be leveraged in targeted attacks on embedded devices or IoT infrastructure that use this IC, impacting sectors such as manufacturing, telecommunications, and critical infrastructure. The vulnerability does not directly expose confidentiality or availability risks but undermines data integrity and system reliability, which are crucial for operational continuity in industrial and embedded environments prevalent in Europe.

European organizations should ensure that their Linux kernel versions include the patch converting FIFO R/W functions to regmap_noinc versions for the SC16IS7XX driver. This involves updating to the latest stable Linux kernel releases or applying vendor-provided patches that address CVE-2023-52488. Embedded system manufacturers and integrators should verify that their device firmware incorporates these fixes. Additionally, organizations should audit their device inventories to identify systems using the SC16IS7XX IC and confirm that kernel versions are up to date. For critical systems, implement monitoring to detect anomalies in serial communication that might indicate cache corruption or data inconsistencies. Where possible, isolate vulnerable embedded devices from untrusted networks to reduce attack surface. Finally, maintain rigorous patch management and coordinate with hardware vendors to ensure timely updates for embedded Linux platforms.