Re: [PATCH v6 2/2] x86/MCE/AMD: Fix memory leak when `threshold_create_bank()` fails

[Thomas Gleixner]

On Tue, Mar 29 2022 at 17:47, Ammar Faizi wrote:

> In mce_threshold_create_device(), if threshold_create_bank() fails, the
> @bp will be leaked, because the call to mce_threshold_remove_device()
> will not free the @bp. mce_threshold_remove_device() frees
> @threshold_banks. At that point, the @bp has not been written to
> @threshold_banks, @threshold_banks is NULL, so the call is just a nop.
>
> Fix this by extracting the cleanup part into a new static function
> __threshold_remove_device(), then call it from create/remove device
> functions.

The way simpler fix is to move 

>  	}
>  	this_cpu_write(threshold_banks, bp);

before the loop. That's safe because the banks cannot yet be reached via
an MCE as the vector is not yet enabled:
  
>  	if (thresholding_irq_en)
>  		mce_threshold_vector = amd_threshold_interrupt;

Thanks,

        tglx