This patch clears mnt_namespace on unmount.
Not clearing mnt_namespace has two effects:
1) It is possible to attach a new mount to a detached mount,
because check_mnt() returns true.
This means, that when no other references to the detached mount
remain, it still can't be freed. This causes a resource leak,
and possibly un-removable modules.
2) If mnt_namespace is dereferenced (only in mark_mounts_for_expiry())
after the namspace has been freed, it can cause an Oops, memory
corruption, etc.
1) has been tested before and after the patch, 2) is only speculation.
Signed-off-by: Miklos Szeredi <[email protected]>
Index: linux/fs/namespace.c
===================================================================
--- linux.orig/fs/namespace.c 2005-05-16 21:02:54.000000000 +0200
+++ linux/fs/namespace.c 2005-05-16 21:20:10.000000000 +0200
@@ -345,6 +345,7 @@ static void umount_tree(struct vfsmount
for (p = mnt; p; p = next_mnt(p, mnt)) {
list_del(&p->mnt_list);
list_add(&p->mnt_list, &kill);
+ p->mnt_namespace = NULL;
}
while (!list_empty(&kill)) {
@@ -1449,15 +1450,8 @@ void __init mnt_init(unsigned long mempa
void __put_namespace(struct namespace *namespace)
{
- struct vfsmount *mnt;
-
down_write(&namespace->sem);
spin_lock(&vfsmount_lock);
-
- list_for_each_entry(mnt, &namespace->list, mnt_list) {
- mnt->mnt_namespace = NULL;
- }
-
umount_tree(namespace->root);
spin_unlock(&vfsmount_lock);
up_write(&namespace->sem);
-
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