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

[Laurent Aimar]

ffmpeg | branch: master | Laurent Aimar <fenrir at videolan.org> | Sat Oct  1 00:45:02 2011 +0200| [346876ec168affe7c21be88d8f1acf1a75cc8409] | 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>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=346876ec168affe7c21be88d8f1acf1a75cc8409
---

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

diff --git a/libavcodec/adpcm.c b/libavcodec/adpcm.c
index 3cb62e3..cf609e7 100644
--- a/libavcodec/adpcm.c
+++ b/libavcodec/adpcm.c
@@ -641,10 +641,11 @@ 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;
         }
@@ -659,6 +660,7 @@ 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);