CVE-2026-43319 spi: spidev: fix lock inversion between spi_lock and buf_lock
A lock inversion in the Linux kernel spidev driver allows local attackers to cause a deadlock and denial of service via concurrent write and ioctl calls.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-43319?
CVE-2026-43319 is a medium-severity vulnerability in Linux kernel, published on 8 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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 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.
Weakness: CWE-667
Which versions are affected by CVE-2026-43319?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43319?
Apply the vendor's patch.
Is CVE-2026-43319 being exploited?
There is no known exploitation of CVE-2026-43319 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-86157, BELL-CVE-2026-43319, DEBIAN-CVE-2026-43319, GHSA-p22q-5w3q-wqpq, ROOT-OS-DEBIAN-11-CVE-2026-43319, ROOT-OS-DEBIAN-12-CVE-2026-43319 and 3 more.