mirror of
https://github.com/Divested-Mobile/DivestOS-Build.git
synced 2024-10-01 01:35:54 -04:00
97 lines
3.0 KiB
Diff
97 lines
3.0 KiB
Diff
|
From 12ca6ad2e3a896256f086497a7c7406a547ee373 Mon Sep 17 00:00:00 2001
|
||
|
|
From: Peter Zijlstra <peterz@infradead.org>
|
||
|
|
Date: Tue, 15 Dec 2015 13:49:05 +0100
|
||
|
|
Subject: perf: Fix race in swevent hash
|
||
|
|
|
||
|
|
There's a race on CPU unplug where we free the swevent hash array
|
||
|
|
while it can still have events on. This will result in a
|
||
|
|
use-after-free which is BAD.
|
||
|
|
|
||
|
|
Simply do not free the hash array on unplug. This leaves the thing
|
||
|
|
around and no use-after-free takes place.
|
||
|
|
|
||
|
|
When the last swevent dies, we do a for_each_possible_cpu() iteration
|
||
|
|
anyway to clean these up, at which time we'll free it, so no leakage
|
||
|
|
will occur.
|
||
|
|
|
||
|
|
Reported-by: Sasha Levin <sasha.levin@oracle.com>
|
||
|
|
Tested-by: Sasha Levin <sasha.levin@oracle.com>
|
||
|
|
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
|
||
|
|
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
|
||
|
|
Cc: Frederic Weisbecker <fweisbec@gmail.com>
|
||
|
|
Cc: Jiri Olsa <jolsa@redhat.com>
|
||
|
|
Cc: Linus Torvalds <torvalds@linux-foundation.org>
|
||
|
|
Cc: Peter Zijlstra <peterz@infradead.org>
|
||
|
|
Cc: Stephane Eranian <eranian@google.com>
|
||
|
|
Cc: Thomas Gleixner <tglx@linutronix.de>
|
||
|
|
Cc: Vince Weaver <vincent.weaver@maine.edu>
|
||
|
|
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
||
|
|
---
|
||
|
|
kernel/events/core.c | 20 +-------------------
|
||
|
|
1 file changed, 1 insertion(+), 19 deletions(-)
|
||
|
|
|
||
|
|
diff --git a/kernel/events/core.c b/kernel/events/core.c
|
||
|
|
index fd7de04..0a791a2 100644
|
||
|
|
--- a/kernel/events/core.c
|
||
|
|
+++ b/kernel/events/core.c
|
||
|
|
@@ -6488,9 +6488,6 @@ 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);
|
||
|
|
@@ -6748,14 +6745,8 @@ 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);
|
||
|
|
perf_event_update_userpage(event);
|
||
|
|
@@ -6823,7 +6814,6 @@ 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;
|
||
|
|
|
||
|
|
@@ -9286,7 +9276,6 @@ static void 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;
|
||
|
|
|
||
|
|
@@ -9328,14 +9317,7 @@ 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) { }
|
||
|
|
--
|
||
|
|
cgit v1.1
|
||
|
|
|