avcodec/get_bits: Make sure the input bitstream with padding can be addressed

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

libavcodec/get_bits.h

@@ -32,6 +32,7 @@
 #include "libavutil/intreadwrite.h"
 #include "libavutil/log.h"
 #include "libavutil/avassert.h"
+#include "avcodec.h"
 #include "mathops.h"
 #include "vlc.h"
 
@@ -428,7 +429,7 @@ static inline int init_get_bits(GetBitContext *s, const uint8_t *buffer,
     int buffer_size;
     int ret = 0;
 
-    if (bit_size >= INT_MAX - 7 || bit_size < 0 || !buffer) {
+    if (bit_size >= INT_MAX - FFMAX(7, AV_INPUT_BUFFER_PADDING_SIZE*8) || bit_size < 0 || !buffer) {
         bit_size    = 0;
         buffer      = NULL;
         ret         = AVERROR_INVALIDDATA;