Merge tag 'v3.10.56' into update

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / kernel / events / core.c

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 6bf387a603998e2786ff70b3abbe5b0b24a7bfa2..cd17762037819d63dee7c1424abf56a989834aa9 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1236,10 +1236,17 @@ static void perf_group_detach(struct perf_event *event)
         * If this was a group event with sibling events then
         * upgrade the siblings to singleton events by adding them
         * to whatever list we are on.
+        * If this isn't on a list, make sure we still remove the sibling's
+        * group_entry from this sibling_list; otherwise, when that sibling
+        * is later deallocated, it will try to remove itself from this
+        * sibling_list, which may well have been deallocated already,
+        * resulting in a use-after-free.
         */
        list_for_each_entry_safe(sibling, tmp, &event->sibling_list, group_entry) {
                if (list)
                        list_move_tail(&sibling->group_entry, list);
+               else
+                       list_del_init(&sibling->group_entry);
                sibling->group_leader = sibling;
 
                /* Inherit group flags from the previous leader */
@@ -5149,9 +5156,6 @@ struct swevent_htable {
 
        /* Recursion avoidance in each contexts */
        int                             recursion[PERF_NR_CONTEXTS];
-
-       /* Keeps track of cpu being initialized/exited */
-       bool                            online;
 };
 
 static DEFINE_PER_CPU(struct swevent_htable, swevent_htable);
@@ -5398,14 +5402,8 @@ static int perf_swevent_add(struct perf_event *event, int flags)
        hwc->state = !(flags & PERF_EF_START);
 
        head = find_swevent_head(swhash, event);
-       if (!head) {
-               /*
-                * We can race with cpu hotplug code. Do not
-                * WARN if the cpu just got unplugged.
-                */
-               WARN_ON_ONCE(swhash->online);
+       if (WARN_ON_ONCE(!head))
                return -EINVAL;
-       }
 
        hlist_add_head_rcu(&event->hlist_entry, head);
 
@@ -5477,7 +5475,6 @@ static int swevent_hlist_get_cpu(struct perf_event *event, int cpu)
        int err = 0;
 
        mutex_lock(&swhash->hlist_mutex);
-
        if (!swevent_hlist_deref(swhash) && cpu_online(cpu)) {
                struct swevent_hlist *hlist;
 
@@ -7506,7 +7503,6 @@ static void __cpuinit perf_event_init_cpu(int cpu)
        struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
 
        mutex_lock(&swhash->hlist_mutex);
-       swhash->online = true;
        if (swhash->hlist_refcount > 0) {
                struct swevent_hlist *hlist;
 
@@ -7559,14 +7555,7 @@ static void perf_event_exit_cpu_context(int cpu)
 
 static void perf_event_exit_cpu(int cpu)
 {
-       struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);
-
        perf_event_exit_cpu_context(cpu);
-
-       mutex_lock(&swhash->hlist_mutex);
-       swhash->online = false;
-       swevent_hlist_release(swhash);
-       mutex_unlock(&swhash->hlist_mutex);
 }
 #else
 static inline void perf_event_exit_cpu(int cpu) { }