1 files changed, 15 insertions, 1 deletions

diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index 0309f2111c70..968e5e0a3f81 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -309,7 +309,7 @@ static int task_is_descendant(struct task_struct *parent,
  * @tracer: the task_struct of the process attempting ptrace
  * @tracee: the task_struct of the process to be ptraced
  *
- * Returns 1 if tracer has is ptracer exception ancestor for tracee.
+ * Returns 1 if tracer has a ptracer exception ancestor for tracee.
  */
 static int ptracer_exception_found(struct task_struct *tracer,
                                    struct task_struct *tracee)
@@ -320,6 +320,18 @@ static int ptracer_exception_found(struct task_struct *tracer,
         bool found = false;
 
         rcu_read_lock();
+
+        /*
+         * If there's already an active tracing relationship, then make an
+         * exception for the sake of other accesses, like process_vm_rw().
+         */
+        parent = ptrace_parent(tracee);
+        if (parent != NULL && same_thread_group(parent, tracer)) {
+                rc = 1;
+                goto unlock;
+        }
+
+        /* Look for a PR_SET_PTRACER relationship. */
         if (!thread_group_leader(tracee))
                 tracee = rcu_dereference(tracee->group_leader);
         list_for_each_entry_rcu(relation, &ptracer_relations, node) {
@@ -334,6 +346,8 @@ static int ptracer_exception_found(struct task_struct *tracer,
 
         if (found && (parent == NULL || task_is_descendant(parent, tracer)))
                 rc = 1;
+
+unlock:
         rcu_read_unlock();
 
         return rc;