spi: spidev: fix lock inversion between spi_lock and buf_lock

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Summary

CVECVE-2026-43319
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-08 14:16:40 UTC
Updated2026-05-08 14:16:40 UTC
DescriptionIn 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.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 f8431b8672231d378b03176fe74c95adfd3522cf git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 e341e18215030af2136836b78508e0d798916df7 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 41ccfac7d302968a4f32b5f7b012d066c5f5cdf8 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 40534d19ed2afb880ecf202dab26a8e7a5808d16 git Not specified
CNA Linux Linux unaffected 6.12.75 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.16 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.6 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/40534d19ed2afb880ecf202dab26a8e7a5808d16 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f8431b8672231d378b03176fe74c95adfd3522cf 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/41ccfac7d302968a4f32b5f7b012d066c5f5cdf8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e341e18215030af2136836b78508e0d798916df7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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