Re: [FFmpeg-devel] [PATCH 1/2] libavfilter/signature_lookup: fix possible division by zero

From: Michael Niedermayer <michael@niedermayer.cc>
To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
Subject: Re: [FFmpeg-devel] [PATCH 1/2] libavfilter/signature_lookup: fix possible division by zero
Date: Tue, 7 May 2024 19:46:28 +0200
Message-ID: <20240507174628.GF6420@pb2> (raw)
In-Reply-To: <20240505223040.521838-1-gerion.entrup@flump.de>

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On Mon, May 06, 2024 at 12:30:39AM +0200, Gerion Entrup wrote:
> ---
>  libavfilter/signature_lookup.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavfilter/signature_lookup.c b/libavfilter/signature_lookup.c
> index a0ca818a9b..b39a3e225b 100644
> --- a/libavfilter/signature_lookup.c
> +++ b/libavfilter/signature_lookup.c
> @@ -128,7 +128,7 @@ static int get_jaccarddist(SignatureContext *sc, CoarseSignature *first, CoarseS
>      int jaccarddist, i, composdist = 0, cwthcount = 0;
>      for (i = 0; i < 5; i++) {
>          if ((jaccarddist = intersection_word(first->data[i], second->data[i])) > 0) {
> -            jaccarddist /= union_word(first->data[i], second->data[i]);
> +            jaccarddist /= FFMAX(union_word(first->data[i], second->data[i]), 1);
>          }

for which input data does this cause a division by 0 ?

thx

[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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