[FFmpeg-cvslog] Fix out of bound reads due to integer overflow in the ADPCM IMA Electronic Arts EACS decoder .

[Laurent Aimar]

ffmpeg | branch: release/0.8 | Laurent Aimar <fenrir at videolan.org> | Sat Oct  1 00:45:02 2011 +0200| [802045777afe0c04cc42ef11f59e273239faaa99] | committer: Michael Niedermayer

Fix out of bound reads due to integer overflow in the ADPCM IMA Electronic Arts EACS decoder.

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
(cherry picked from commit 346876ec168affe7c21be88d8f1acf1a75cc8409)

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=802045777afe0c04cc42ef11f59e273239faaa99
---

 libavcodec/adpcm.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/libavcodec/adpcm.c b/libavcodec/adpcm.c
index ba31255..de7bc7a 100644
--- a/libavcodec/adpcm.c
+++ b/libavcodec/adpcm.c
@@ -1333,10 +1333,11 @@ static int adpcm_decode_frame(AVCodecContext *avctx,
             buf_size -= 128;
         }
         break;
-    case CODEC_ID_ADPCM_IMA_EA_EACS:
+    case CODEC_ID_ADPCM_IMA_EA_EACS: {
+        unsigned header_size = 4 + (8<<st);
         samples_in_chunk = bytestream_get_le32(&src) >> (1-st);
 
-        if (samples_in_chunk > buf_size-4-(8<<st)) {
+        if (buf_size < header_size || samples_in_chunk > buf_size - header_size) {
             src += buf_size - 4;
             break;
         }
@@ -1351,6 +1352,7 @@ static int adpcm_decode_frame(AVCodecContext *avctx,
             *samples++ = adpcm_ima_expand_nibble(&c->status[st], *src&0x0F, 3);
         }
         break;
+    }
     case CODEC_ID_ADPCM_IMA_EA_SEAD:
         for (; src < buf+buf_size; src++) {
             *samples++ = adpcm_ima_expand_nibble(&c->status[0], src[0] >> 4, 6);