libavcodec/mpegaudiodecheader.h : detect reserved mpeg id

Check the MPEG version ID for the reserved bit pattern 01, and abort the
header check in that case. This reduces the chance of misinterpreting
arbitrary data as a valid header, and prevents resulting audio artifacts.

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

diff --git a/libavcodec/mpegaudiodecheader.h b/libavcodec/mpegaudiodecheader.h
index 1cb9216461ab03f810910547303d4b08d7776df7..ed9961250afbea3b63f440431d0a0ac9515322c4 100644 (file)
--- a/libavcodec/mpegaudiodecheader.h
+++ b/libavcodec/mpegaudiodecheader.h
@@ -62,6 +62,9 @@ static inline int ff_mpa_check_header(uint32_t header){
     /* header */
     if ((header & 0xffe00000) != 0xffe00000)
         return -1;
+    /* version check */
+    if ((header & (3<<19)) == 1)
+        return -1;
     /* layer check */
     if ((header & (3<<17)) == 0)
         return -1;