CVE-2021-47195 Information

Description

In the Linux kernel the following vulnerability has been resolved:

spi: fix use-after-free of the add_lock mutex

Commit 6098475d4cb4 (\spi: Fix deadlock when adding SPI controllers on SPI buses) introduced a per-controller mutex. But mutex_unlock() of said lock is called after the controller is already freed:

spi_unregister_controller(ctlr) -> put_device(&ctlr->dev) -> spi_controller_release(dev) -> mutex_unlock(&ctrl->add_lock)

Move the put_device() after the mutex_unlock().

Reference

https://git.kernel.org/stable/c/37330f37f6666c7739a44b2b6b95b047ccdbed2d https://git.kernel.org/stable/c/6c53b45c71b4920b5e62f0ea8079a1da382b9434