[FFmpeg-cvslog] avcodec/aacdec_fixed: Limit index in vector_pow43()

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Mon Oct 12 17:11:27 2020 +0200| [4f83a536384afda45acb6d7cdd22017c8c314f9e] | committer: Michael Niedermayer

avcodec/aacdec_fixed: Limit index in vector_pow43()

Fixes: out of array access
Fixes: 26087/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AAC_FIXED_fuzzer-5724825462767616

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=4f83a536384afda45acb6d7cdd22017c8c314f9e
---

 libavcodec/aacdec_fixed.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/aacdec_fixed.c b/libavcodec/aacdec_fixed.c
index 9b2145c729..daaf765e0c 100644
--- a/libavcodec/aacdec_fixed.c
+++ b/libavcodec/aacdec_fixed.c
@@ -155,9 +155,9 @@ static void vector_pow43(int *coefs, int len)
     for (i=0; i<len; i++) {
         coef = coefs[i];
         if (coef < 0)
-            coef = -(int)ff_cbrt_tab_fixed[-coef];
+            coef = -(int)ff_cbrt_tab_fixed[(-coef) & 8191];
         else
-            coef = (int)ff_cbrt_tab_fixed[coef];
+            coef =  (int)ff_cbrt_tab_fixed[  coef  & 8191];
         coefs[i] = coef;
     }
 }