CVE-2026-43319

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

spi: spidev: fix lock inversion between spi_lock and buf_lock

The spidev driver previously used two mutexes, spi_lock and buf_lock,

but acquired them in different orders depending on the code path:

write()/read(): buf_lock -> spi_lock

ioctl(): spi_lock -> buf_lock

This AB-BA locking pattern triggers lockdep warnings and can

cause real deadlocks:

WARNING: possible circular locking dependency detected

spidev_ioctl() -> mutex_lock(&spidev->buf_lock)

spidev_sync_write() -> mutex_lock(&spidev->spi_lock)

*** DEADLOCK ***

The issue is reproducible with a simple userspace program that

performs write() and SPI_IOC_WR_MAX_SPEED_HZ ioctl() calls from

separate threads on the same spidev file descriptor.

Fix this by simplifying the locking model and removing the lock

inversion entirely. spidev_sync() no longer performs any locking,

and all callers serialize access using spi_lock.

buf_lock is removed since

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References