[FFmpeg-cvslog] aacpsy: avoid psy_band->threshold becoming NaN

[Andreas Cadhalpun]

ffmpeg | branch: release/2.4 | Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com> | Thu Apr 16 20:04:54 2015 +0200| [6458ee5af8f994f2f8e42a3a4a2f407b978103f4] | committer: Michael Niedermayer

aacpsy: avoid psy_band->threshold becoming NaN

If band->thr is 0.0f, the division is undefined, making norm_fac not a
number or infinity, which causes psy_band->threshold to become NaN.

This is passed on to other variables until it finally reaches
sce->sf_idx and is converted to an integer (-2147483648).

This causes a segmentation fault when it is used as array index.

Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>
Reviewed-by: Claudio Freire <klaussfreire at gmail.com>
Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
(cherry picked from commit e224aa41917454e7b5c23d9f2541425743ce595a)

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=6458ee5af8f994f2f8e42a3a4a2f407b978103f4
---

 libavcodec/aacpsy.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libavcodec/aacpsy.c b/libavcodec/aacpsy.c
index 9eeb836..cee4bf2 100644
--- a/libavcodec/aacpsy.c
+++ b/libavcodec/aacpsy.c
@@ -727,7 +727,10 @@ static void psy_3gpp_analyze_channel(FFPsyContext *ctx, int channel,
                     if (active_lines > 0.0f)
                         band->thr = calc_reduced_thr_3gpp(band, coeffs[g].min_snr, reduction);
                     pe += calc_pe_3gpp(band);
-                    band->norm_fac = band->active_lines / band->thr;
+                    if (band->thr > 0.0f)
+                        band->norm_fac = band->active_lines / band->thr;
+                    else
+                        band->norm_fac = 0.0f;
                     norm_fac += band->norm_fac;
                 }
             }