This function must provide guarantees for readers, that
ve_ns != NULL under rcu_read_lock means the rest of context
(say, ve->init_task) is table.
But now order is wrong, and it does not guarantee that. Fix it.
v2: Use local variable for ve_ns, otherwise net_ns write results
in NULL pointer derefence.
Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com>
---
kernel/ve/ve.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/kernel/ve/ve.c b/kernel/ve/ve.c
index db26cbd41d3f..cfc3039bb85b 100644
--- a/kernel/ve/ve.c
+++ b/kernel/ve/ve.c
@@ -579,15 +579,18 @@ static void ve_stop_kthread(struct ve_struct *ve)
static void ve_grab_context(struct ve_struct *ve)
{
struct task_struct *tsk = current;
+ struct nsproxy *ve_ns;
get_task_struct(tsk);
ve->init_task = tsk;
ve->root_css_set = tsk->cgroups;
get_css_set(ve->root_css_set);
ve->init_cred = (struct cred *)get_current_cred();
- rcu_assign_pointer(ve->ve_ns, get_nsproxy(tsk->nsproxy));
- ve->ve_netns = get_net(ve->ve_ns->net_ns);
+ ve_ns = get_nsproxy(tsk->nsproxy);
+ ve->ve_netns = get_net(ve_ns->net_ns);
synchronize_rcu();
+
+ rcu_assign_pointer(ve->ve_ns, ve_ns);
}
static void ve_drop_context(struct ve_struct *ve)
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