clear the size of the storage, not the size of the pointer

--- a/usr/md5.c
+++ b/usr/md5.c
@@ -127,7 +127,7 @@ MD5Final(md5byte digest[16], struct MD5Context *ctx)
 
 	byteSwap(ctx->buf, 4);
 	memcpy(digest, ctx->buf, 16);
-	memset(ctx, 0, sizeof(ctx));	/* In case it's sensitive */
+	memset(ctx, 0, sizeof(*ctx));	/* In case it's sensitive */
 }
 
 #ifndef ASM_MD5
--- a/utils/md5.c
+++ b/utils/md5.c
@@ -133,7 +133,7 @@ MD5Final(md5byte digest[16], struct MD5Context *ctx)
 
 	byteSwap(ctx->buf, 4);
 	memcpy(digest, ctx->buf, 16);
-	memset(ctx, 0, sizeof (ctx));	/* In case it's sensitive */
+	memset(ctx, 0, sizeof (*ctx));	/* In case it's sensitive */
 }
 
 #ifndef ASM_MD5