fix: don't allow userspace copy to read kernel memory

[lttng-modules.git] / lttng-context-prio.c

diff --git a/lttng-context-prio.c b/lttng-context-prio.c
index b5d21e7e9438bafee3779d483532745f1ec1e65b..c786f5d312d644094da09479e61b9991a8e838f5 100644 (file)
--- a/lttng-context-prio.c
+++ b/lttng-context-prio.c
@@ -29,6 +29,19 @@ int wrapper_task_prio_init(void)
        return 0;
 }
 
+/*
+ * Canary function to check for 'task_prio()' at compile time.
+ *
+ * From 'include/linux/sched.h':
+ *
+ *   extern int task_prio(const struct task_struct *p);
+ */
+__attribute__((unused)) static
+int __canary__task_prio(const struct task_struct *p)
+{
+       return task_prio(p);
+}
+
 static
 size_t prio_get_size(size_t offset)
 {
@@ -89,7 +102,7 @@ int lttng_add_prio_to_ctx(struct lttng_ctx **ctx)
        field->record = prio_record;
        field->get_value = prio_get_value;
        lttng_context_update(*ctx);
-       wrapper_vmalloc_sync_all();
+       wrapper_vmalloc_sync_mappings();
        return 0;
 }
 EXPORT_SYMBOL_GPL(lttng_add_prio_to_ctx);