[FFmpeg-cvslog] avcodec/aacpsy: Avoid floating point division by 0 of norm_fac

[Michael Niedermayer]

ffmpeg | branch: release/4.4 | Michael Niedermayer <michael at niedermayer.cc> | Fri May 28 20:18:25 2021 +0200| [5828700d5c70aaec1f10c417975123c76262bd98] | committer: Michael Niedermayer

avcodec/aacpsy: Avoid floating point division by 0 of norm_fac

Fixes: Ticket7995
Fixes: CVE-2020-20446

Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 223b5e8ac9f6461bb13ed365419ec485c5b2b002)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=5828700d5c70aaec1f10c417975123c76262bd98
---

 libavcodec/aacpsy.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libavcodec/aacpsy.c b/libavcodec/aacpsy.c
index fca692cb15..bd444fecdc 100644
--- a/libavcodec/aacpsy.c
+++ b/libavcodec/aacpsy.c
@@ -794,7 +794,7 @@ static void psy_3gpp_analyze_channel(FFPsyContext *ctx, int channel,
 
         if (pe < 1.15f * desired_pe) {
             /* 6.6.1.3.6 "Final threshold modification by linearization" */
-            norm_fac = 1.0f / norm_fac;
+            norm_fac = norm_fac ? 1.0f / norm_fac : 0;
             for (w = 0; w < wi->num_windows*16; w += 16) {
                 for (g = 0; g < num_bands; g++) {
                     AacPsyBand *band = &pch->band[w+g];