avcodec/iff: add forgotten checks for end of input buffer

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavcodec/iff.c

@@ -1247,7 +1247,7 @@ static void decode_delta_d(uint8_t *dst,
         bytestream2_init(&gb, buf + ofssrc, buf_end - (buf + ofssrc));
 
         entries = bytestream2_get_be32(&gb);
-        while (entries) {
+        while (entries && bytestream2_get_bytes_left(&gb) >= 8) {
             int32_t opcode  = bytestream2_get_be32(&gb);
             unsigned offset = bytestream2_get_be32(&gb);
 
@@ -1302,7 +1302,7 @@ static void decode_delta_e(uint8_t *dst,
         bytestream2_init(&gb, buf + ofssrc, buf_end - (buf + ofssrc));
 
         entries = bytestream2_get_be16(&gb);
-        while (entries) {
+        while (entries && bytestream2_get_bytes_left(&gb) >= 6) {
             int16_t opcode  = bytestream2_get_be16(&gb);
             unsigned offset = bytestream2_get_be32(&gb);