2003-09-02 10:40:43

by Vladimir Kondratiev

[permalink] [raw]
Subject: [PATCH] Resource leak in reparent_to_init

In reparent_to_init, it is clear bug that causes resource leak. It is
pretty easy to test that this bug causes problems: if your module allows
to create thread for non-root user (using daemonize() and
reparent_to_init()), it will mis-count number of processes running for
that user.
Patch follows.
P.S. I do not subscribed to the list, thus please in your reply CC me
([email protected])

--- kernel/sched.c.orig 2003-08-17 20:12:14.000000000 +0300
+++ kernel/sched.c 2003-08-17 21:21:08.000000000 +0300
@@ -1274,8 +1274,16 @@
this_task->cap_permitted = CAP_FULL_SET;
this_task->keep_capabilities = 0;
memcpy(this_task->rlim, init_task.rlim, sizeof(*(this_task->rlim)));
- this_task->user = INIT_USER;
-
+ if (this_task->uid) { /* not root? switch user */
+ struct user_struct *old_user = this_task->user,
+ *new_user = INIT_USER;
+ this_task->uid = 0;
+ this_task->user = new_user;
+ atomic_inc(&new_user->__count);
+ atomic_inc(&new_user->processes);
+ atomic_dec(&old_user->processes);
+ free_uid(old_user);
+ }
spin_unlock(&runqueue_lock);
write_unlock_irq(&tasklist_lock);
}