Re: 2.6.23-rc6-mm1 - make access to tasks nsproxy ligther (fix)

Cedric Le Goater
2007-09-20T08:42:11Z

Hello !

Andrew Morton wrote:
> ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.23-rc6/2.6.23-rc6-mm1/

make-access-to-tasks-nsproxy-lighter.patch breaks unshare()

when called from unshare(), switch_task_namespaces() takes an
extra refcount on the nsproxy, leading to a memory leak of
nsproxy objects.

Now the problem is that we still need that extra ref when called
from daemonize(). Here's an ugly fix for it.

Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
---
include/linux/nsproxy.h | 5 +++++
kernel/exit.c | 2 ++
kernel/nsproxy.c | 7 -------
3 files changed, 7 insertions(+), 7 deletions(-)

Index: 2.6.23-rc6-mm1/kernel/nsproxy.c
===================================================================
--- 2.6.23-rc6-mm1.orig/kernel/nsproxy.c
+++ 2.6.23-rc6-mm1/kernel/nsproxy.c
@@ -25,11 +25,6 @@ static struct kmem_cache *nsproxy_cachep

struct nsproxy init_nsproxy = INIT_NSPROXY(init_nsproxy);

-static inline void get_nsproxy(struct nsproxy *ns)
-{
- atomic_inc(&ns->count);
-}
-
/*
* creates a copy of "orig" with refcount 1.
*/
@@ -208,8 +203,6 @@ void switch_task_namespaces(struct task_
if (ns == new)
return;

- if (new)
- get_nsproxy(new);
rcu_assign_pointer(p->nsproxy, new);

if (ns && atomic_dec_and_test(&ns->count)) {
Index: 2.6.23-rc6-mm1/kernel/exit.c
===================================================================
--- 2.6.23-rc6-mm1.orig/kernel/exit.c
+++ 2.6.23-rc6-mm1/kernel/exit.c
@@ -408,6 +408,8 @@ void daemonize(const char *name, ...)
current->fs = fs;
atomic_inc(&fs->count);

+ if (current->nsproxy != init_task.nsproxy)
+ get_nsproxy(init_task.nsproxy);
switch_task_namespaces(current, init_task.nsproxy);

exit_files(current);
Index: 2.6.23-rc6-mm1/include/linux/nsproxy.h
===================================================================
--- 2.6.23-rc6-mm1.orig/include/linux/nsproxy.h
+++ 2.6.23-rc6-mm1/include/linux/nsproxy.h
@@ -77,6 +77,11 @@ static inline void put_nsproxy(struct ns
}
}

+static inline void get_nsproxy(struct nsproxy *ns)
+{
+ atomic_inc(&ns->count);
+}
+
#ifdef CONFIG_CONTAINER_NS
int ns_container_clone(struct task_struct *tsk);
#else