[FFmpeg-devel] [PATCH 1/1] libavformat/mov: Add bound checks to avoid integer overflow and invalid memory allocation

["zhilizhao(赵志立)"]

> On Oct 19, 2020, at 10:42 AM, Xiaohui Zhang <ruc_zhangxiaohui at 163.com> wrote:
> 
> From: Zhang Xiaohui <ruc_zhangxiaohui at 163.com>
> 
> Hi, I think function mov_read_cmov fails to perform proper bounds
> checking on atom.size and cmov_len, which may lead to integer
> overflow and invalid memory allocation.
> 
> Signed-off-by: Zhang Xiaohui <ruc_zhangxiaohui at 163.com>
> ---
> libavformat/mov.c | 4 ++++
> 1 file changed, 4 insertions(+)
> 
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 7fd43a8fc5..245c720e42 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -5181,8 +5181,12 @@ static int mov_read_cmov(MOVContext *c, AVIOContext *pb, MOVAtom atom)
>     if (avio_rl32(pb) != MKTAG('c','m','v','d'))
>         return AVERROR_INVALIDDATA;
>     moov_len = avio_rb32(pb); /* uncompressed size */
> +    if (atom.size > LONG_MAX + 6 * 4)
> +        return AVERROR_INVALIDDATA;

LONG_MAX + 6 * 4 leads to overflow.

>     cmov_len = atom.size - 6 * 4;
> 
> +    if (cmov_len <= 0)
> +        return AVERROR_INVALIDDATA;
>     cmov_data = av_malloc(cmov_len);
>     if (!cmov_data)
>         return AVERROR(ENOMEM);
> -- 
> 2.17.1
> 
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