CyberRota Analysis
AI-GeneratedThe vulnerability affects the Linux kernel's SPI (Serial Peripheral Interface) subsystem, specifically in the handling of DMA (Direct Memory Access) mappings during transfer operations. If a receive mapping fails after a transmit mapping has succeeded, it can lead to improper management of mapping states, potentially resulting in NULL dereferences and system crashes. Organizations utilizing Linux systems with SPI interfaces should prioritize addressing this issue to prevent potential instability and ensure reliable operation of their hardware interactions.
Original NVD Description
In the Linux kernel, the following vulnerability has been resolved: spi: Fix DMA mapping ownership on partial map failure If RX mapping fails after TX mapping succeeds, __spi_map_msg() unmaps TX but leaves tx_sg_mapped set. If TX mapping fails on a later transfer, mappings created for earlier transfers remain active. In both cases, cur_{tx,rx}_dma_dev have not yet been updated because they are assigned only after every transfer has been mapped. The subsequent spi_unmap_msg() may therefore unmap the TX mapping again or release earlier mappings using a NULL or stale device. Using a NULL device can trigger an oops. An empty SG table does not prevent the NULL dereference because dma_unmap_sg_attrs() accesses the device before checking the entry count. Publish both mapping devices before mapping starts and unwind all failures through __spi_unmap_msg(). This clears the mapping flags and releases each mapping once with the device that created it. Publishing the devices before the loop also refreshes them when no transfer needs mapping. No mapping flag is set in that case, so current users do not use the pointers as mapping owners.