md5 memset

[Ted Unangst]

memset length found by jsg.  missing free found by me.

maybe the free was deliberate to avoid optimizing away memset?  I think
it's still wrong to do that though.

Index: md5.c
===================================================================
RCS file: /home/tedu/cvs/src/bin/md5/md5.c,v
retrieving revision 1.52
diff -u -p -r1.52 md5.c
--- md5.c       27 Oct 2010 15:24:10 -0000      1.52
+++ md5.c       5 Jul 2011 18:22:20 -0000
@@ -415,7 +415,8 @@ digest_end(const struct hash_function *h
                hf->final(digest, ctx);
                if (b64_ntop(digest, hf->digestlen, buf, bsize) == -1)
                        errx(1, "error encoding base64");
-               memset(digest, 0, sizeof(digest));
+               memset(digest, 0, hf->digestlen);
+               free(digest);
        } else {
                hf->end(ctx, buf);
        }