1 files changed, 12 insertions, 0 deletions

diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index f5d332cf8c63..adc785146a1c 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -139,6 +139,18 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
                 goto out;
         }
 
+        /*
+         * CLONE_NEWIPC must detach from the undolist: after switching
+         * to a new ipc namespace, the semaphore arrays from the old
+         * namespace are unreachable.  In clone parlance, CLONE_SYSVSEM
+         * means share undolist with parent, so we must forbid using
+         * it along with CLONE_NEWIPC.
+         */
+        if ((flags & CLONE_NEWIPC) && (flags & CLONE_SYSVSEM)) {
+                err = -EINVAL;
+                goto out;
+        }
+
         new_ns = create_new_namespaces(flags, tsk, tsk->fs);
         if (IS_ERR(new_ns)) {
                 err = PTR_ERR(new_ns);