intel_pmu: fix for possible null pointer dereference

Null pointer dereference could occur for invalid first hardware event.
In pmu_add_hw_events if the first event was not resolved, on the second
iteration the eventlist_last could be dereferenced to mark previous
event as group leader.

Change-Id: Ic2a2a3572d6835ca892d71f3e66812f356592d9e
Signed-off-by: Kamil Wiatrowski <kamilx.wiatrowski@intel.com>

diff --git a/src/intel_pmu.c b/src/intel_pmu.c
index fd2bd6f..e0d796f 100644 (file)
--- a/src/intel_pmu.c
+++ b/src/intel_pmu.c
@@ -204,6 +204,11 @@ static int pmu_config_hw_events(oconfig_item_t *ci) {
     return -EINVAL;
   }
 
+  if (g_ctx.hw_events) {
+    ERROR(PMU_PLUGIN ": Duplicate config for HardwareEvents.");
+    return -EINVAL;
+  }
+
   g_ctx.hw_events = calloc(ci->values_num, sizeof(char *));
   if (g_ctx.hw_events == NULL) {
     ERROR(PMU_PLUGIN ": Failed to allocate hw events.");
@@ -401,12 +406,6 @@ static int pmu_add_hw_events(struct eventlist *el, char **e, size_t count) {
     char *s, *tmp;
     for (s = strtok_r(events, ",", &tmp); s; s = strtok_r(NULL, ",", &tmp)) {
 
-      /* Multiple events parsed in one entry */
-      if (group_events_count == 1) {
-        /* Mark previously added event as group leader */
-        el->eventlist_last->group_leader = 1;
-      }
-
       /* Allocate memory for event struct that contains array of efd structs
          for all cores */
       struct event *e =
@@ -416,19 +415,26 @@ static int pmu_add_hw_events(struct eventlist *el, char **e, size_t count) {
         return -ENOMEM;
       }
 
-      if (resolve_event(s, &e->attr) == 0) {
-        e->next = NULL;
-        if (!el->eventlist)
-          el->eventlist = e;
-        if (el->eventlist_last)
-          el->eventlist_last->next = e;
-        el->eventlist_last = e;
-        e->event = strdup(s);
-      } else {
-        DEBUG(PMU_PLUGIN ": Cannot resolve %s", s);
+      if (resolve_event(s, &e->attr) != 0) {
+        WARNING(PMU_PLUGIN ": Cannot resolve %s", s);
         sfree(e);
+        continue;
       }
 
+      /* Multiple events parsed in one entry */
+      if (group_events_count == 1) {
+        /* Mark previously added event as group leader */
+        el->eventlist_last->group_leader = 1;
+      }
+
+      e->next = NULL;
+      if (!el->eventlist)
+        el->eventlist = e;
+      if (el->eventlist_last)
+        el->eventlist_last->next = e;
+      el->eventlist_last = e;
+      e->event = strdup(s);
+
       group_events_count++;
     }