[FFmpeg-devel] [PATCH] aacpsy: avoid norm_fac becoming NaN

[Andreas Cadhalpun]

If both band->active_lines and band->thr are 0.0f, the division is
undefined, making norm_fac not a number.

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

diff --git a/libavcodec/aacpsy.c b/libavcodec/aacpsy.c
index d1e65f6..b71933b 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->active_lines != 0.0f)
+                        band->norm_fac = band->active_lines / band->thr;
+                    else
+                        band->norm_fac = 0.0f;
                     norm_fac += band->norm_fac;
                 }
             }
-- 
2.1.4