Fix crash when changing data points (#2062802)

Resolves: #2062802

gnome-system-monitor-40.1-changing-points-crash.patch

@@ -0,0 +1,78 @@
+From cc5200c00aa82894a97ac0a89efe19fcb9db5260 Mon Sep 17 00:00:00 2001
+From: Sergey Bugaev <bugaevc@gmail.com>
+Date: Sat, 1 May 2021 14:23:33 +0300
+Subject: [PATCH] Fix crash when changing the number of points
+
+std::rotate accepts an "end" iterator that points one after the last
+item. In plain C, it's possible to create a "one past end" pointer by
+using the following idiom: &arr[size], which is equivalent to arr + size.
+No actual pointer dereference happens in this case. In C++, vector[index]
+always causes a vector.operator[](index) invocation; it is undefined
+behavior to use this method with out-of-bounds indexes. Therefore, this
+idiom cannot be used in C++ to get a "one past end" iterator. Instead,
+C++ provides .begin() and .end() methods. Use those instead.
+
+Fixes https://gitlab.gnome.org/GNOME/gnome-system-monitor/-/issues/197
+Fixes https://gitlab.gnome.org/GNOME/gnome-system-monitor/-/issues/181
+---
+ src/load-graph.cpp | 23 +++++++++--------------
+ 1 file changed, 9 insertions(+), 14 deletions(-)
+
+diff --git a/src/load-graph.cpp b/src/load-graph.cpp
+index b18bc61c..aa28589f 100644
+--- a/src/load-graph.cpp
++++ b/src/load-graph.cpp
+@@ -792,9 +792,9 @@ void
+ load_graph_update_data (LoadGraph *graph)
+ {
+     // Rotate data one element down.
+-    std::rotate(&graph->data[0],
+-                &graph->data[graph->num_points - 2],
+-                &graph->data[graph->num_points - 1]);
++    std::rotate(graph->data.begin(),
++                graph->data.end() - 1,
++                graph->data.end());
+ 
+     // Update rotation counter.
+     graph->latest = (graph->latest + 1) % graph->num_points;
+@@ -1061,31 +1061,26 @@ void
+ load_graph_change_num_points(LoadGraph *graph,
+                              guint new_num_points)
+ {
+-    //Don't do anything if the value didn't change.
++    // Don't do anything if the value didn't change.
+     if (graph->num_points == new_num_points)
+         return;
+ 
+     // Sort the values in the data_block vector in the order they were accessed in by the pointers in data.
+-    std::rotate(&graph->data_block[0],
+-                &graph->data_block[(graph->num_points - graph->latest) * graph->n],
+-                &graph->data_block[graph->num_points * graph->n]);
++    std::rotate(graph->data_block.begin(),
++                graph->data_block.begin() + (graph->num_points - graph->latest) * graph->n,
++                graph->data_block.end());
+ 
+     // Reset rotation counter.
+     graph->latest = 0;
+ 
+     // Resize the vectors to the new amount of data points.
++    // Fill the new values with -1.
+     graph->data.resize(new_num_points);
+-    graph->data_block.resize(graph->n * new_num_points);
++    graph->data_block.resize(graph->n * new_num_points, -1.0);
+     if (graph->type == LOAD_GRAPH_NET) {
+         graph->net.values.resize(new_num_points);
+     }
+ 
+-    // Fill the new values with -1 instead of 0 if the vectors got bigger.
+-    if (new_num_points > graph->num_points) {
+-        std::fill(&graph->data_block[graph->n * graph->num_points],
+-                  &graph->data_block[graph->n * new_num_points], -1.0);
+-    }
+-
+     // Replace the pointers in data, to match the new data_block values.
+     for (guint i = 0; i < new_num_points; ++i) {
+         graph->data[i] = &graph->data_block[0] + i * graph->n;
+-- 
+2.36.1
+

gnome-system-monitor.spec

@@ -12,6 +12,8 @@ URL:            https://wiki.gnome.org/Apps/SystemMonitor
 Source0:        https://download.gnome.org/sources/%{name}/40/%{name}-%{tarball_version}.tar.xz
 # https://bugzilla.redhat.com/show_bug.cgi?id=2073741
 Patch0:         gnome-system-monitor-40.1-help-shortcut.patch
+# https://bugzilla.redhat.com/show_bug.cgi?id=2062802
+Patch1:         gnome-system-monitor-40.1-changing-points-crash.patch
 
 BuildRequires:  gcc
 BuildRequires:  gcc-c++
@@ -70,6 +72,7 @@ desktop-file-validate $RPM_BUILD_ROOT%{_datadir}/applications/gnome-system-monit
 %changelog
 * Wed May 11 2022 David King <amigadave@amigadave.com> - 40.1-3
 - Fix help overlay shortcut (#2073741)
+- Fix crash when changing data points (#2062802)
 
 * Mon Aug 09 2021 Mohan Boddu <mboddu@redhat.com> - 40.1-2
 - Rebuilt for IMA sigs, glibc 2.34, aarch64 flags