linux-kernel - Re: [PATCH] media: videobuf2: Fix integer overrun in allocation

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Date:   Wed, 10 Mar 2021 09:49:20 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Ricardo Ribalda <ribalda@...omium.org>
Cc:     Tomasz Figa <tfiga@...omium.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] media: videobuf2: Fix integer overrun in allocation

Hi Ricardo,

Thank you for the patch.

On Wed, Mar 10, 2021 at 12:43:17AM +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.
> 
> Cc: stable@...r.kernel.org
> Fixes: 7f8414594e47 ("[media] media: videobuf2: fix the length check for mmap")
> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> ---
>  drivers/media/common/videobuf2/videobuf2-core.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
> index 02281d13505f..543da515c761 100644
> --- a/drivers/media/common/videobuf2/videobuf2-core.c
> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> @@ -223,8 +223,10 @@ static int __vb2_buf_mem_alloc(struct vb2_buffer *vb)
>  	 * NOTE: mmapped areas should be page aligned
>  	 */
>  	for (plane = 0; plane < vb->num_planes; ++plane) {
> +		unsigned long size = vb->planes[plane].length;

unsigned long is still 32-bit on 32-bit platforms.

> +
>  		/* Memops alloc requires size to be page aligned. */
> -		unsigned long size = PAGE_ALIGN(vb->planes[plane].length);
> +		size = PAGE_ALIGN(size);
>  
>  		/* Did it wrap around? */
>  		if (size < vb->planes[plane].length)

Doesn't this address the issue already ?


-- 
Regards,

Laurent Pinchart