linux-kernel - Re: [PATCH] nsproxy cloning error path fix

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Date:	Thu, 31 Aug 2006 06:59:07 -0500
From:	"Serge E. Hallyn" <serue@...ibm.com>
To:	Pavel <xemul@...nvz.org>
Cc:	Andrew Morton <akpm@...l.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Serge Hallyn <serue@...ibm.com>, ebiederm@...ssion.com,
	clg@...ibm.com, Kirill Korotaev <dev@...nvz.org>
Subject: Re: [PATCH] nsproxy cloning error path fix

Quoting Pavel (xemul@...nvz.org):
> This patch fixes copy_namespaces()'s error path.
> 
> when new nsproxy (new_ns) is created pointers to namespaces (ipc, uts)
> are copied from the old nsproxy. Later in copy_utsname, copy_ipcs, etc.
> according namespaces are get-ed. On error path needed namespaces are
> put-ed, so there's no need to put new nsproxy itelf as it woud cause
> putting namespaces for the second time.
> 
> Found when incorporating namespaces into OpenVZ kernel.
> 
> Signed-off-by: Pavel Emelianov <xemul@...nvz.org>

Acked-by: Serge Hallyn <serue@...ibm.com>

> ---
> 
>  nsproxy.c |    2 +-
>  1 files changed, 1 insertion(+), 1 deletion(-)
> 
> --- ./kernel/nsproxy.c.veboot	2006-08-30 17:48:59.000000000 +0400
> +++ ./kernel/nsproxy.c	2006-08-31 10:54:56.000000000 +0400
> @@ -115,7 +115,7 @@ out_uts:
>  		put_namespace(new_ns->namespace);
>  out_ns:
>  	tsk->nsproxy = old_ns;
> -	put_nsproxy(new_ns);
> +	kfree(new_ns);
>  	goto out;
>  }

Yes, thanks.

The logic has subtly changed since the last version I'd sent out.  I
have tests which should have caught this, and need to start firing off
jobs to periodically test them against -mm.

In fact I notice that it is currently no longer putting old_ns on the
error path.  Seems to me the following patch should be needed on top
of yours.

Meanwhile I'll start firing off a test against v2.6.18-rc4-mm3.

thanks,
-serge

>From c4d187c3c1534c22e7879d52eeceed55412c9559 Mon Sep 17 00:00:00 2001
From: Serge E. Hallyn <serue@...ibm.com>
Date: Thu, 31 Aug 2006 06:54:15 -0500
Subject: [PATCH 1/1] nsproxy: free the old_ns on copy_namespaces error

copy_namespaces increments the usage count on old_ns at top.
On successful exit it properly decrements that usage count.
On error path it failed to do so.

Signed-off-by: Serge E. Hallyn <serue@...ibm.com>
---
 kernel/nsproxy.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c
index e25d97c..575155a 100644
--- a/kernel/nsproxy.c
+++ b/kernel/nsproxy.c
@@ -121,6 +121,7 @@ out_uts:
 out_ns:
 	tsk->nsproxy = old_ns;
 	kfree(new_ns);
+	put_nsproxy(old_ns);
 	goto out;
 }
 
-- 
1.4.2

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