Fix valgrind-check and memory leak

Can you believe that we ware testing the memory leak with valgrind
to just *bash scripts* instead of actual binaries on liberasurecode_test
and libec_slap?

That is why we cannot find such an easy memory leak[1] at the gate.
Now this patch enable to run the valgrind against to the binaries.

With this fix, we found various memory leak at liberasurecode_test as
follows and this patch also fixes them:

- If we create fake fragments, we're responsible for freeing all of the
  frags as well as the array holding the pointers to the frags.
- If we allocate any space, we're responsible for freeing it.
- If we create an EC descriptor, we're responsible for destroying it.
- If we create a fragment or skip array, we're responsible for freeing it.
- If that happens inside a loop, we're responsible for doing it *inside
  that same loop*.

In addition to the test fix, this patch fixes following memory leaks at
the code which is affected to other users (pyeclib, OpenStack Swift)

* Refuse to decode fragments that aren't even long enough to include
  fragment headers.
* Fix a small memory leak in the builtin rs_vand implementation.

Closes-Bug: #1665242

Co-Authored-By: Tim Burke <tim@swiftstack.com>

1: https://review.openstack.org/#/c/431812

Change-Id: I96f124e4e536bbd7544208acc084de1cda5c19b2

2 files changed, 8 insertions, 1 deletions

diff --git a/src/builtin/rs_vand/liberasurecode_rs_vand.c b/src/builtin/rs_vand/liberasurecode_rs_vand.c
index de88d34..94b1620 100644
--- a/src/builtin/rs_vand/liberasurecode_rs_vand.c
+++ b/src/builtin/rs_vand/liberasurecode_rs_vand.c
@@ -543,7 +543,7 @@ int liberasurecode_rs_vand_reconstruct(int *generator_matrix, char **data, char
     }
     region_dot_product(first_k_available, parity[destination_idx - k], parity_row, k, blocksize);
   }
-  
+  free(parity_row);
   free(decoding_matrix);
   free(inverse_decoding_matrix);
   free(first_k_available);
diff --git a/src/erasurecode.c b/src/erasurecode.c
index a63bc25..6206b47 100644
--- a/src/erasurecode.c
+++ b/src/erasurecode.c
@@ -587,6 +587,13 @@ int liberasurecode_decode(int desc,
         goto out;
     }
 
+    if (fragment_len < sizeof(fragment_header_t)) {
+        log_error("Fragments not long enough to include headers! "
+                  "Need %zu, but got %lu.", sizeof(fragment_header_t),
+                  (unsigned long)fragment_len);
+        ret = -EBADHEADER;
+        goto out;
+    }
     for (i = 0; i < num_fragments; ++i) {
         /* Verify metadata checksum */
         if (is_invalid_fragment_header(