[FFmpeg-cvslog] avcodec/aacdec_template (fixed point): Check gain in decode_cce() to avoid undefined shifts later

[Michael Niedermayer]

ffmpeg | branch: release/2.8 | Michael Niedermayer <michael at niedermayer.cc> | Sat Jul 15 22:22:52 2017 +0200| [1b1abf077d642fe38c2fd133cf18c99d4d7141b4] | committer: Michael Niedermayer

avcodec/aacdec_template (fixed point): Check gain in decode_cce() to avoid undefined shifts later

Fixes: runtime error: shift exponent 47 is too large for 32-bit type 'int'
Fixes: 2581/clusterfuzz-testcase-minimized-4681474395602944

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 2886142e0c3b5f4304c6e2a2bd282770a8a47f93)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=1b1abf077d642fe38c2fd133cf18c99d4d7141b4
---

 libavcodec/aacdec_template.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/libavcodec/aacdec_template.c b/libavcodec/aacdec_template.c
index 2920d06ece..1b119f7c66 100644
--- a/libavcodec/aacdec_template.c
+++ b/libavcodec/aacdec_template.c
@@ -2161,6 +2161,10 @@ static int decode_cce(AACContext *ac, GetBitContext *gb, ChannelElement *che)
             cge = coup->coupling_point == AFTER_IMDCT ? 1 : get_bits1(gb);
             gain = cge ? get_vlc2(gb, vlc_scalefactors.table, 7, 3) - 60: 0;
             gain_cache = GET_GAIN(scale, gain);
+#if USE_FIXED
+            if ((abs(gain_cache)-1024) >> 3 > 30)
+                return AVERROR(ERANGE);
+#endif
         }
         if (coup->coupling_point == AFTER_IMDCT) {
             coup->gain[c][0] = gain_cache;
@@ -2178,6 +2182,10 @@ static int decode_cce(AACContext *ac, GetBitContext *gb, ChannelElement *che)
                                     t >>= 1;
                                 }
                                 gain_cache = GET_GAIN(scale, t) * s;
+#if USE_FIXED
+                                if ((abs(gain_cache)-1024) >> 3 > 30)
+                                    return AVERROR(ERANGE);
+#endif
                             }
                         }
                         coup->gain[c][idx] = gain_cache;