Re: [PATCH 1/1] staging: ion: Prevent incorrect reference counting behavour

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Apr 25, 2022 at 04:51:54PM +0100, Lee Jones wrote:
> Supply additional check in order to prevent unexpected results.
> 
> Fixes: b892bf75b2034 ("ion: Switch ion to use dma-buf")
> Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: Lee Jones <lee.jones@linaro.org>
> ---
> This is a forward-port from linux-4.4.y and linux-4.9.y.
> 
> It has never been upstream.
> 
> Please apply to v4.14 through v5.10.
> 
>  drivers/staging/android/ion/ion.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
> index e1fe03ceb7f13..e6d4a3ee6cda5 100644
> --- a/drivers/staging/android/ion/ion.c
> +++ b/drivers/staging/android/ion/ion.c
> @@ -114,6 +114,9 @@ static void *ion_buffer_kmap_get(struct ion_buffer *buffer)
>  	void *vaddr;
>  
>  	if (buffer->kmap_cnt) {
> +		if (buffer->kmap_cnt == INT_MAX)
> +			return ERR_PTR(-EOVERFLOW);
> +
>  		buffer->kmap_cnt++;
>  		return buffer->vaddr;
>  	}
> -- 
> 2.36.0.rc2.479.g8af0fa9b8e-goog
> 

Now queued up, thanks.

gre gk-h