linux-kernel - [27/70] CRED: Fix memory and refcount leaks upon security_prepare

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Date:	Tue, 22 Feb 2011 14:17:06 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	David Howells <dhowells@...hat.com>
Subject: [27/70] CRED: Fix memory and refcount leaks upon security_prepare_creds() failure

2.6.37-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>

commit fb2b2a1d37f80cc818fd4487b510f4e11816e5e1 upstream.

In prepare_kernel_cred() since 2.6.29, put_cred(new) is called without
assigning new->usage when security_prepare_creds() returned an error.  As a
result, memory for new and refcount for new->{user,group_info,tgcred} are
leaked because put_cred(new) won't call __put_cred() unless old->usage == 1.

Fix these leaks by assigning new->usage (and new->subscribers which was added
in 2.6.32) before calling security_prepare_creds().

Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Signed-off-by: David Howells <dhowells@...hat.com>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 kernel/cred.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -657,6 +657,8 @@ struct cred *prepare_kernel_cred(struct
 	validate_creds(old);
 
 	*new = *old;
+	atomic_set(&new->usage, 1);
+	set_cred_subscribers(new, 0);
 	get_uid(new->user);
 	get_group_info(new->group_info);
 
@@ -674,8 +676,6 @@ struct cred *prepare_kernel_cred(struct
 	if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
 		goto error;
 
-	atomic_set(&new->usage, 1);
-	set_cred_subscribers(new, 0);
 	put_cred(old);
 	validate_creds(new);
 	return new;


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