On Thu, Mar 07, 2019 at 09:18:42PM +0100, Michael Niedermayer wrote: > On Thu, Mar 07, 2019 at 09:45:12AM +0800, Jun Zhao 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 | 7 +++++++ > > 1 files changed, 7 insertions(+), 0 deletions(-) > > > > diff --git a/libavfilter/vf_nlmeans.c b/libavfilter/vf_nlmeans.c > > index dcb5a03..9876aae 100644 > > --- a/libavfilter/vf_nlmeans.c > > +++ b/libavfilter/vf_nlmeans.c > > @@ -236,6 +236,13 @@ static void compute_ssd_integral_image(const > > NLMeansDSPContext *dsp, > > // adjusted end x position of the safe area after width of the safe > > area gets aligned > > const int endx_safe = startx_safe + safe_pw; > > > > + // 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. > > + if ((UINT32_MAX / (uint64_t)w) < (255 * (uint64_t)h)) > > + av_log(NULL, AV_LOG_WARNING, > > + "image (%d x %d) integral value may overflow.\n", w ,h); > > Printing a warning is not an adequate response for a integer overflow. > Such thing is undefined behavior (in case signed of signed int) and must > not occur.
And if no signed ints are involved, while this is then not undefined it still gives the wrong result. Thats a bug, the bug should be fixed not a warning be printed that the bug might be triggered Thanks [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB There will always be a question for which you do not know the correct answer.
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