CVE-2022-48696 in Linux
Summary
by MITRE • 05/03/2024
In the Linux kernel, the following vulnerability has been resolved:
regmap: spi: Reserve space for register address/padding
Currently the max_raw_read and max_raw_write limits in regmap_spi struct do not take into account the additional size of the transmitted register address and padding. This may result in exceeding the maximum permitted SPI message size, which could cause undefined behaviour, e.g. data corruption.
Fix regmap_get_spi_bus() to properly adjust the above mentioned limits by reserving space for the register address/padding as set in the regmap configuration.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 09/29/2025
The vulnerability identified as CVE-2022-48696 resides within the Linux kernel's regmap subsystem, specifically affecting SPI-based register map implementations. This issue impacts the proper calculation of maximum read and write limits for SPI messages, creating a potential pathway for data corruption and system instability. The flaw manifests in the regmap_spi structure where the max_raw_read and max_raw_write parameters fail to account for the additional overhead required for register address transmission and padding bytes that are necessary for proper SPI communication protocols. This oversight directly violates the fundamental principles of secure system design where resource boundaries must be accurately calculated to prevent buffer overflows and memory corruption scenarios.
The technical root cause of this vulnerability stems from improper boundary calculations within the regmap_get_spi_bus() function which is responsible for configuring SPI message parameters. When the kernel attempts to construct SPI messages for register operations, it fails to reserve adequate space for the register address field and any required padding bytes that must be transmitted alongside the actual register data. This miscalculation can cause the total SPI message size to exceed the hardware or driver-defined limits, resulting in truncated messages or buffer overflows. The vulnerability operates at the intersection of hardware abstraction layers and kernel subsystems, making it particularly dangerous as it can affect various SPI-based devices including sensors, memory chips, and communication controllers that rely on regmap for register access operations.
The operational impact of this vulnerability extends beyond simple data corruption to potentially compromise system integrity and availability. When SPI message limits are exceeded, the kernel may either silently truncate data transmissions or generate malformed SPI frames that cause device communication failures. This can lead to complete device unresponsiveness, incorrect sensor readings, or even system crashes depending on the criticality of the affected hardware components. The vulnerability affects any system utilizing SPI-based devices that employ the regmap framework for register management, which encompasses a broad range of embedded systems, IoT devices, and server hardware. From an attack perspective, this represents a potential privilege escalation vector where malicious actors could exploit the buffer overflow conditions to corrupt system memory or manipulate device states, particularly in environments where SPI devices are used for critical system functions.
Security mitigations for this vulnerability require updating to kernel versions that include the patched regmap_get_spi_bus() function which properly accounts for register address and padding space requirements. System administrators should prioritize kernel updates across all affected systems, particularly those operating in security-sensitive environments or managing critical infrastructure. The fix implements proper boundary calculations by incorporating the register address size and padding requirements as defined in the regmap configuration structure, effectively preventing SPI message size overruns. Additionally, implementing runtime monitoring for SPI communication errors and establishing proper logging of register access operations can help detect potential exploitation attempts. Organizations should also review their SPI device configurations to ensure proper alignment between hardware capabilities and software expectations, as this vulnerability highlights the importance of precise resource management in kernel subsystems. The fix addresses the underlying CWE-129 weakness related to improper validation of array indices and buffer overflows, while also aligning with ATT&CK techniques focused on privilege escalation and system resource manipulation through kernel-level vulnerabilities.