Re: [PATCH 5.10] staging: gasket: interrupt: Clean interrupt_data after free

[Greg Kroah-Hartman]

On Mon, May 15, 2023 at 03:29:50PM +0300, Esina Ekaterina wrote:
> Add interrupt_data = NULL after kfree(interrupt_data) in
> gasket_interrupt_init. It is needed to avoid double free
> in gasket_interrupt_cleanup, there is a check for NULL
> before kfree(interrupt_data).
> 
> Found by Astra Linux on behalf of Linux Verification Center
> (linuxtesting.org) with SVACE.
> 
> Fixes: 9a69f5087ccc ("drivers/staging: Gasket driver framework + Apex driver")
> Signed-off-by: Esina Ekaterina <eesina@xxxxxxxxxxxxx>
> ---
>  drivers/staging/gasket/gasket_interrupt.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/staging/gasket/gasket_interrupt.c b/drivers/staging/gasket/gasket_interrupt.c
> index 864342acfd86..48b664b9134a 100644
> --- a/drivers/staging/gasket/gasket_interrupt.c
> +++ b/drivers/staging/gasket/gasket_interrupt.c
> @@ -337,6 +337,7 @@ int gasket_interrupt_init(struct gasket_dev *gasket_dev)
>  			sizeof(*interrupt_data->eventfd_ctxs), GFP_KERNEL);
>  	if (!interrupt_data->eventfd_ctxs) {
>  		kfree(interrupt_data);
> +		interrupt_data = NULL;
>  		return -ENOMEM;
>  	}
>  
> @@ -346,6 +347,7 @@ int gasket_interrupt_init(struct gasket_dev *gasket_dev)
>  	if (!interrupt_data->interrupt_counts) {
>  		kfree(interrupt_data->eventfd_ctxs);
>  		kfree(interrupt_data);
> +		interrupt_data = NULL;
>  		return -ENOMEM;
>  	}
>  
> -- 
> 2.40.1

Also, your tool is wrong, this is not a correct fix at all.

How did you test it?  Why is your tool spitting out incorrect code?  Why
are you not verifying it's output before asking others to do so?

Please don't do this anymore, it's wasteful on our side, right?  Please
take the time to review existing changes for problems, that would be
more useful overall to everyone.

thanks,

greg k-h