From: Miklos Szeredi <miklos@szeredi.hu>
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 <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
fs/namespace.c | 8 +-------
1 files changed, 1 insertion(+), 7 deletions(-)
diff -puN fs/namespace.c~namespacec-fix-mnt_namespace-clearing fs/namespace.c
--- 25/fs/namespace.c~namespacec-fix-mnt_namespace-clearing Mon May 16 14:56:47 2005
+++ 25-akpm/fs/namespace.c Mon May 16 14:56:47 2005
@@ -345,6 +345,7 @@ void umount_tree(struct vfsmount *mnt)
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);
_