On Thursday 17 July 2014 09:41:40 pm Nicolas George wrote:
> Le nonidi 29 messidor, an CCXXII, Carl Eugen Hoyos a écrit :
> >
> > Attached patch fixes ticket #3777 for me, analyzed by Oliver
> > Fromme.
> I would suggest to avoid floating point arithmetic if possible.
> Possibly something like that:
>
> uint64_t min = FFMIN(fsize, mp3->header_filesize);
> uint64_t delta = FFMAX(fsize, mp3->header_filesize) - min;
> uint64_t tolerance = min / 20;
> if (... && min - tolerance < 2 * tolerance)
>
> I also find this version easier to understand.
Thank you, new patch attached.
> I can not judge on the correctness, though.
The logic is copied from asfdec.c.
Please review, Carl Eugen
diff --git a/libavformat/mp3dec.c b/libavformat/mp3dec.c
index 8335388..cf5aa73 100644
--- a/libavformat/mp3dec.c
+++ b/libavformat/mp3dec.c
@@ -138,6 +138,7 @@ static void mp3_parse_info_tag(AVFormatContext *s, AVStream
*st,
MP3DecContext *mp3 = s->priv_data;
static const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
+ uint64_t min, delta, fsize = avio_size(s->pb);
/* Check for Xing / Info tag */
avio_skip(s->pb, xing_offtbl[c->lsf == 1][c->nb_channels == 1]);
@@ -151,6 +152,10 @@ static void mp3_parse_info_tag(AVFormatContext *s,
AVStream *st,
mp3->frames = avio_rb32(s->pb);
if (v & XING_FLAG_SIZE)
mp3->header_filesize = avio_rb32(s->pb);
+ min = FFMIN(fsize, mp3->header_filesize);
+ delta = FFMAX(fsize, mp3->header_filesize) - min;
+ if (fsize && mp3->header_filesize > 0 && delta > min >> 4)
+ mp3->frames = 0;
if (v & XING_FLAG_TOC)
read_xing_toc(s, mp3->header_filesize, av_rescale_q(mp3->frames,
(AVRational){spf, c->sample_rate},
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