filestore: fix crash if keyword setup fails

SigMatch would be added to list, then the alproto check failed, leading
to freeing of sm. But as it was still in the list, the list now contained
a dangling pointer.

src/detect-filestore.c

@@ -411,9 +411,6 @@ static int DetectFilestoreSetup (DetectEngineCtx *de_ctx, Signature *s, char *st
         sm->ctx = NULL;
     }
 
-    SigMatchAppendSMToList(s, sm, DETECT_SM_LIST_FILEMATCH);
-    s->filestore_sm = sm;
-
     if (s->alproto != ALPROTO_HTTP && s->alproto != ALPROTO_SMTP) {
         SCLogError(SC_ERR_CONFLICTING_RULE_KEYWORDS, "rule contains conflicting keywords.");
         goto error;
@@ -423,6 +420,9 @@ static int DetectFilestoreSetup (DetectEngineCtx *de_ctx, Signature *s, char *st
         AppLayerHtpNeedFileInspection();
     }
 
+    SigMatchAppendSMToList(s, sm, DETECT_SM_LIST_FILEMATCH);
+    s->filestore_sm = sm;
+
     s->flags |= SIG_FLAG_FILESTORE;
     return 0;