For matches, only copy the subject string if it is not already in workspace.

src/vmod_re2.c

@@ -150,11 +150,13 @@ match(VRT_CTX, vre2 * restrict vre2, VCL_STRING restrict subject,
 	snap = WS_Snapshot(ctx->ws);
 	if (!never_capture) {
 		ngroups++;
-		if ((text = WS_Copy(ctx->ws, subject, len + 1)) == NULL) {
-			VERR(ctx, ERR_PREFIX "insufficient workspace to copy "
-			     "subject", subject);
-			return 0;
-		}
+		if (!WS_Inside(ctx->ws, subject, subject + len + 1))
+			if ((text = WS_Copy(ctx->ws, subject, len + 1))
+			    == NULL) {
+				VERR(ctx, ERR_PREFIX "insufficient workspace "
+				     "to copy subject", subject);
+				return 0;
+			}
 		if ((*groups = WS_Alloc(ctx->ws, ngroups * match_sz))
 		    == NULL) {
 			VERR(ctx, ERR_PREFIX "insufficient workspace to "