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Diffstat (limited to 'kernel/events/core.c')
-rw-r--r--kernel/events/core.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 7858bafffa9d..7f1e4c5897e7 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -12217,6 +12217,9 @@ SYSCALL_DEFINE5(perf_event_open,
* Do not allow to attach to a group in a different task
* or CPU context. If we're moving SW events, we'll fix
* this up later, so allow that.
+ *
+ * Racy, not holding group_leader->ctx->mutex, see comment with
+ * perf_event_ctx_lock().
*/
if (!move_group && group_leader->ctx != ctx)
goto err_context;
@@ -12282,6 +12285,7 @@ SYSCALL_DEFINE5(perf_event_open,
} else {
perf_event_ctx_unlock(group_leader, gctx);
move_group = 0;
+ goto not_move_group;
}
}
@@ -12298,7 +12302,17 @@ SYSCALL_DEFINE5(perf_event_open,
}
} else {
mutex_lock(&ctx->mutex);
+
+ /*
+ * Now that we hold ctx->lock, (re)validate group_leader->ctx == ctx,
+ * see the group_leader && !move_group test earlier.
+ */
+ if (group_leader && group_leader->ctx != ctx) {
+ err = -EINVAL;
+ goto err_locked;
+ }
}
+not_move_group:
if (ctx->task == TASK_TOMBSTONE) {
err = -ESRCH;