On 3/8/19, myp...@gmail.com <myp...@gmail.com> wrote:
> On Fri, Mar 8, 2019 at 5:26 PM Paul B Mahol <one...@gmail.com> wrote:
>>
>> On 3/8/19, Jun Zhao <mypopy...@gmail.com> wrote:
>> > From: Jun Zhao <barryjz...@tencent.com>
>> >
>> > accumulation of 8-bits uint_8 (uint8_t *src) into 32-bits (uint32_t *ii)
>> > data type, it will have a risk of an integral value becoming larger than
>> > the 32-bits integer capacity and resulting in an integer overflow. For
>> > this risk, add a checking with warning message.
>> >
>> > Signed-off-by: Jun Zhao <barryjz...@tencent.com>
>> > ---
>> > libavfilter/vf_nlmeans.c | 11 +++++++++++
>> > 1 files changed, 11 insertions(+), 0 deletions(-)
>> >
>> > diff --git a/libavfilter/vf_nlmeans.c b/libavfilter/vf_nlmeans.c
>> > index dcb5a03..8d47f9d 100644
>> > --- a/libavfilter/vf_nlmeans.c
>> > +++ b/libavfilter/vf_nlmeans.c
>> > @@ -477,6 +477,17 @@ static int filter_frame(AVFilterLink *inlink,
>> > AVFrame
>> > *in)
>> > NLMeansContext *s = ctx->priv;
>> > AVFilterLink *outlink = ctx->outputs[0];
>> >
>> > + // accumulation of 8-bits uint_8 into 32-bits data type, it will
>> > have
>> > + // a risk of an integral value becoming larger than the 32-bits
>> > integer
>> > + // capacity and resulting in an integer overflow, so limit the
>> > image
>> > size
>> > + if ((UINT32_MAX / (uint64_t)inlink->w) < (255 *
>> > (uint64_t)inlink->h)) {
>> > + av_log(ctx, AV_LOG_ERROR,
>> > + "image size (%d x %d) integral value may overflow.\n",
>> > + inlink->w, inlink->h);
>> > + av_frame_free(&in);
>> > + return AVERROR(EINVAL);
>> > + }
>> > +
>> > AVFrame *out = ff_get_video_buffer(outlink, outlink->w,
>> > outlink->h);
>> > if (!out) {
>> > av_frame_free(&in);
>>
>> I see no point in this warning, if overflow is real issue should be
>> fixed instead of giving
>> pointless warning.
> In fact, this is a potential overflow problems depend on image
> value/width/height when calculating integral image(Summed-area_table
> is the other name https://en.wikipedia.org/wiki/Summed-area_table),
> this is the reason to limit the image size in this patch to avoid this
> potential overflow problems, I don't know what's the mean for " should
> be fixed instead of giving pointless warning.", can you give more
> information for this? thx.
Use uint64_t type.
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