oma: don't read beyond end of leaf_table.

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org

libavformat/omadec.c

@@ -231,7 +231,7 @@ static int decrypt_init(AVFormatContext *s, ID3v2ExtraMeta *em, uint8_t *header)
         rprobe(s, gdata, oc->r_val) < 0 &&
         nprobe(s, gdata, oc->n_val) < 0) {
         int i;
-        for (i = 0; i < sizeof(leaf_table); i += 2) {
+        for (i = 0; i < FF_ARRAY_ELEMS(leaf_table); i += 2) {
             uint8_t buf[16];
             AV_WL64(buf, leaf_table[i]);
             AV_WL64(&buf[8], leaf_table[i+1]);