avcodec/wmaprodec: Fix buflen computation in save_bits()

Fixes: Assertion failure
Fixes: 18630/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WMAPRO_fuzzer-5201588654440448
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

diff --git a/libavcodec/wmaprodec.c b/libavcodec/wmaprodec.c
index e001dd6e4eb28a86fa0d5afd38a7fb81cc3e7117..87e2ead693fb081b2fbf454b98411550434554cb 100644 (file)
--- a/libavcodec/wmaprodec.c
+++ b/libavcodec/wmaprodec.c
@@ -1565,9 +1565,9 @@ static void save_bits(WMAProDecodeCtx *s, GetBitContext* gb, int len,
         s->frame_offset = get_bits_count(gb) & 7;
         s->num_saved_bits = s->frame_offset;
         init_put_bits(&s->pb, s->frame_data, MAX_FRAMESIZE);
-    }
-
-    buflen = (put_bits_count(&s->pb) + len + 8) >> 3;
+        buflen = (s->num_saved_bits      + len + 7) >> 3;
+    } else
+        buflen = (put_bits_count(&s->pb) + len + 7) >> 3;
 
     if (len <= 0 || buflen > MAX_FRAMESIZE) {
         avpriv_request_sample(s->avctx, "Too small input buffer");