All tests should give some portion of data to the producer and use the rest.

tests/fuzz/stream_round_trip.c

@@ -125,15 +125,15 @@ static size_t compress(uint8_t *dst, size_t capacity,
 
 int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)
 {
-    size_t neededBufSize;
-    neededBufSize = ZSTD_compressBound(size) * 5;
-
     /* Give a random portion of src data to the producer, to use for
     parameter generation. The rest will be used for (de)compression */
     FUZZ_dataProducer_t *producer = FUZZ_dataProducer_create(src, size);
     size_t producerSliceSize = FUZZ_dataProducer_uint32Range(producer, 0, size);
     size = FUZZ_dataProducer_contract(producer, producerSliceSize);
 
+    size_t neededBufSize;
+    neededBufSize = ZSTD_compressBound(size) * 5;
+
     /* Allocate all buffers and contexts if not already allocated */
     if (neededBufSize > bufSize) {
         free(cBuf);