Avoid use-after-free in C-EDF deallocate.

Some day, we should implement proper plugin switching...
For now, this should suffice to avoid crashes.

1 files changed, 14 insertions, 14 deletions

diff --git a/litmus/sched_cedf.c b/litmus/sched_cedf.c
index c715ec1e0ee2..fba4fd5b2a59 100644
--- a/litmus/sched_cedf.c
+++ b/litmus/sched_cedf.c
@@ -605,24 +605,21 @@ static void print_cluster_topology(cpumask_var_t mask, int cpu)
 }
 #endif
 
+static int clusters_allocated = 0;
+
 static void cleanup_cedf(void)
 {
         int i;
-        for (i = 0; i < num_clusters; i++) {
-                kfree(cedf[i].cpus);
-                kfree(cedf[i].heap_node);
-                free_cpumask_var(cedf[i].cpu_map);
-        }
 
-        kfree(cedf);
-}
-
-static long cedf_deactivate_plugin(void)
-{
-        cleanup_cedf();
-        printk(KERN_INFO "C-EDF: Deactivate Plugin\n");
+        if (clusters_allocated) {
+                for (i = 0; i < num_clusters; i++) {
+                        kfree(cedf[i].cpus);
+                        kfree(cedf[i].heap_node);
+                        free_cpumask_var(cedf[i].cpu_map);
+                }
 
-        return 0;
+                kfree(cedf);
+        }
 }
 
 static long cedf_activate_plugin(void)
@@ -633,6 +630,9 @@ static long cedf_activate_plugin(void)
         cpumask_var_t mask;
         int chk = 0;
 
+        /* de-allocate old clusters, if any */
+        cleanup_cedf();
+
         printk(KERN_INFO "C-EDF: Activate Plugin, cache index = %d\n",
                         cluster_cache_index);
 
@@ -722,6 +722,7 @@ static long cedf_activate_plugin(void)
         }
 
         free_cpumask_var(mask);
+        clusters_allocated = 1;
         return 0;
 }
 
@@ -738,7 +739,6 @@ static struct sched_plugin cedf_plugin __cacheline_aligned_in_smp = {
         .task_block             = cedf_task_block,
         .admit_task             = cedf_admit_task,
         .activate_plugin        = cedf_activate_plugin,
-        .deactivate_plugin      = cedf_deactivate_plugin,
 };