Re: [PATCH v2] media: videobuf2: Fix integer overrun in vb2_mmap

[Tomasz Figa]

On Wed, Mar 10, 2021 at 08:51:27AM +0100, Ricardo Ribalda wrote:
> The plane_length is an unsigned integer. So, if we have a size of
> 0xffffffff bytes we incorrectly allocate 0 bytes instead of 1 << 32.
> 
> Suggested-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 7f8414594e47 ("[media] media: videobuf2: fix the length check for mmap")
> Reviewed-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
> Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
> ---
>  drivers/media/common/videobuf2/videobuf2-core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
> index 543da515c761..89c8bacb94a7 100644
> --- a/drivers/media/common/videobuf2/videobuf2-core.c
> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> @@ -2256,7 +2256,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
>  	 * The buffer length was page_aligned at __vb2_buf_mem_alloc(),
>  	 * so, we need to do the same here.
>  	 */
> -	length = PAGE_ALIGN(vb->planes[plane].length);
> +	length = PAGE_ALIGN((unsigned long)vb->planes[plane].length);
>  	if (length < (vma->vm_end - vma->vm_start)) {
>  		dprintk(q, 1,
>  			"MMAP invalid, as it would overflow buffer length\n");
> -- 
> 2.30.1.766.gb4fecdf3b7-goog
> 

Acked-by: Tomasz Figa <tfiga@xxxxxxxxxxxx>

Best regards,
Tomasz