diff options
authorEric W. Biederman <ebiederm@xmission.com>2012-12-20 19:26:06 -0800
committerEric W. Biederman <ebiederm@xmission.com>2012-12-24 22:53:14 -0800
commit8382fcac1b813ad0a4e68a838fc7ae93fa39eda0 (patch)
parenta49f0d1ea3ec94fc7cf33a7c36a16343b74bd565 (diff)
pidns: Outlaw thread creation after unshare(CLONE_NEWPID)
The sequence: unshare(CLONE_NEWPID) clone(CLONE_THREAD|CLONE_SIGHAND|CLONE_VM) Creates a new process in the new pid namespace without setting pid_ns->child_reaper. After forking this results in a NULL pointer dereference. Avoid this and other nonsense scenarios that can show up after creating a new pid namespace with unshare by adding a new check in copy_prodcess. Pointed-out-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
1 files changed, 8 insertions, 0 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index a31b823b3c2..65ca6d27f24 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1166,6 +1166,14 @@ static struct task_struct *copy_process(unsigned long clone_flags,
current->signal->flags & SIGNAL_UNKILLABLE)
return ERR_PTR(-EINVAL);
+ /*
+ * If the new process will be in a different pid namespace
+ * don't allow the creation of threads.
+ */
+ if ((clone_flags & (CLONE_VM|CLONE_NEWPID)) &&
+ (task_active_pid_ns(current) != current->nsproxy->pid_ns))
+ return ERR_PTR(-EINVAL);
retval = security_task_create(clone_flags);
if (retval)
goto fork_out;