[FFmpeg-devel] [PATCH 1/2] lavc/aac_ac3_parser: fix the potential overflow

[Jun Zhao]

From: Jun Zhao <barryjzhao at tencent.com>

Fix the potential overflow.

Suggested-by: Alexander Strasser <eclipse7 at gmx.net>
Signed-off-by: Jun Zhao <barryjzhao at tencent.com>
---
 libavcodec/aac_ac3_parser.c         | 9 +++++----
 libavcodec/aac_ac3_parser.h         | 4 ++--
 tests/ref/fate/adtstoasc_ticket3715 | 2 +-
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/libavcodec/aac_ac3_parser.c b/libavcodec/aac_ac3_parser.c
index 0746798..b26790d 100644
--- a/libavcodec/aac_ac3_parser.c
+++ b/libavcodec/aac_ac3_parser.c
@@ -98,11 +98,12 @@ get_next:
         }
 
         /* Calculate the average bit rate */
-        s->frame_number++;
         if (avctx->codec_id != AV_CODEC_ID_EAC3) {
-            avctx->bit_rate =
-                (s->last_bit_rate * (s->frame_number -1) + s->bit_rate)/s->frame_number;
-            s->last_bit_rate = avctx->bit_rate;
+            if (s->frame_number < UINT64_MAX) {
+                s->frame_number++;
+                s->last_bit_rate += (s->bit_rate - s->last_bit_rate)/s->frame_number;
+                avctx->bit_rate = (int64_t)llround(s->last_bit_rate);
+            }
         }
     }
 
diff --git a/libavcodec/aac_ac3_parser.h b/libavcodec/aac_ac3_parser.h
index b04041f..c53d16f 100644
--- a/libavcodec/aac_ac3_parser.h
+++ b/libavcodec/aac_ac3_parser.h
@@ -55,8 +55,8 @@ typedef struct AACAC3ParseContext {
     uint64_t state;
 
     int need_next_header;
-    int frame_number;
-    int last_bit_rate;
+    uint64_t frame_number;
+    double last_bit_rate;
     enum AVCodecID codec_id;
 } AACAC3ParseContext;
 
diff --git a/tests/ref/fate/adtstoasc_ticket3715 b/tests/ref/fate/adtstoasc_ticket3715
index 3b473ee..63e577a 100644
--- a/tests/ref/fate/adtstoasc_ticket3715
+++ b/tests/ref/fate/adtstoasc_ticket3715
@@ -1,4 +1,4 @@
-3e63cbb6bb6ec756d79fab2632fef305 *tests/data/fate/adtstoasc_ticket3715.mov
+feb8a43e4b7df2a4763bd9d55153c900 *tests/data/fate/adtstoasc_ticket3715.mov
 33324 tests/data/fate/adtstoasc_ticket3715.mov
 #extradata 0:        2, 0x00340022
 #tb 0: 1/44100
-- 
2.7.4