CVE-2024-49985

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

i2c: stm32f7: Do not prepare/unprepare clock during runtime suspend/resume

In case there is any sort of clock controller attached to this I2C bus controller, for example Versaclock or even an AIC32x4 I2C codec, then an I2C transfer triggered from the clock controller clkops .prepare callback may trigger a deadlock on drivers/clk/clk.c preparelock mutex.

This is because the clock controller first grabs the preparelock mutex and then performs the prepare operation, including its I2C access. The I2C access resumes this I2C bus controller via .runtimeresume callback, which calls clkprepareenable(), which attempts to grab the prepare_lock mutex again and deadlocks.

Since the clock are already prepared since probe() and unprepared in remove(), use simple clkenable()/clkdisable() calls to enable and disable the clock on runtime suspend and resume, to avoid hitting the prepare_lock mutex.