From: John W. O'Brien <john@saltant.com>
Date: Sat, 14 Mar 2020 12:49:47 +0000 (-0400)
Subject: Fix double meaning of time 0 as uninitialized value
X-Git-Tag: v1.8.0~42^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=refs%2Fpull%2F1079%2Fhead;p=thirdparty%2Frrdtool-1.x.git

Fix double meaning of time 0 as uninitialized value

Treat "VRULE:0#..." as "VRULE:1#..." because elsewhere xrule==0 is
used to mean xrule has not been set, which can lead to an array
bounds violation.
---

diff --git a/src/rrd_graph_helper.c b/src/rrd_graph_helper.c
index ceb009a4..f88893b4 100644
--- a/src/rrd_graph_helper.c
+++ b/src/rrd_graph_helper.c
@@ -1026,6 +1026,10 @@ static graph_desc_t *newGraphDescription(
                     }
                     if (gf == GF_VRULE) {
                         gdp->xrule = val;
+                        if (gdp->xrule == 0) {
+                            /* distinguish from uninitialized */
+                            gdp->xrule++;
+                        }
                     } else {
                         gdp->yrule = val;
                     }