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Subject: Re: [PATCH] media: videobuf2: Fix integer overrun in vb2_mmap
To:     Ricardo Ribalda <ribalda@chromium.org>,
        Tomasz Figa <tfiga@chromium.org>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Sergey Senozhatsky <senozhatsky@chromium.org>,
        stable@vger.kernel.org
References: <20210310074028.1042475-1-ribalda@chromium.org>
From:   Jiri Slaby <jslaby@suse.cz>
Message-ID: <48e8ffd7-7f42-8e22-bf9d-646d9bd89bd9@suse.cz>
Date:   Wed, 10 Mar 2021 08:47:51 +0100
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On 10. 03. 21, 8:40, 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@chromium.org>
> Cc: stable@vger.kernel.org
> Fixes: 7f8414594e47 ("[media] media: videobuf2: fix the length check for mmap")
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
>   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..876db5886867 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 int)vb->planes[plane].length);

Hi,

I fail to see how case from uint to uint helps -- IOW, did you mean ulong?

regards,
-- 
js
suse labs