CVE-2026-43319
Beschrijving NL
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 depend ency 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 its functionality is fully covered by
spi_lock, eliminating the possibility of lock ordering issues. This removes the lock inversion and prevents deadlocks without
changing userspace ABI or behaviour.
Origineel (Engels) tonen
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 its functionality is fully covered by
spi_lock, eliminating the possibility of lock ordering issues.
This removes the lock inversion and prevents deadlocks without
changing userspace ABI or behaviour.