avcodec/utils, avcodec_open2: close codec on failure

after a successful init if the function fails for another reason close
the codec without requiring FF_CODEC_CAP_INIT_CLEANUP which is meant to
cover init failures themselves. fixes a memory leak in those cases.

BUG=oss-fuzz:15529

Signed-off-by: James Zern <jzern@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/utils.c

@@ -542,6 +542,7 @@ int attribute_align_arg ff_codec_open2_recursive(AVCodecContext *avctx, const AV
 int attribute_align_arg avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options)
 {
     int ret = 0;
+    int codec_init_ok = 0;
     AVDictionary *tmp = NULL;
     const AVPixFmtDescriptor *pixdesc;
 
@@ -935,6 +936,7 @@ FF_ENABLE_DEPRECATION_WARNINGS
         if (ret < 0) {
             goto free_and_end;
         }
+        codec_init_ok = 1;
     }
 
     ret=0;
@@ -1023,7 +1025,8 @@ end:
     return ret;
 free_and_end:
     if (avctx->codec &&
-        (avctx->codec->caps_internal & FF_CODEC_CAP_INIT_CLEANUP))
+        (codec_init_ok ||
+         (avctx->codec->caps_internal & FF_CODEC_CAP_INIT_CLEANUP)))
         avctx->codec->close(avctx);
 
     if (codec->priv_class && codec->priv_data_size)