Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754574Ab2JGXXH (ORCPT ); Sun, 7 Oct 2012 19:23:07 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:38395 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754069Ab2JGXWi (ORCPT ); Sun, 7 Oct 2012 19:22:38 -0400 Message-Id: <20121007225845.086900587@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Sun, 07 Oct 2012 23:59:49 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Mathias Krause , Steffen Klassert , "David S. Miller" Subject: [ 075/108] xfrm_user: return error pointer instead of NULL In-Reply-To: <20121007225834.673681075@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1830 Lines: 57 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mathias Krause [ Upstream commit 864745d291b5ba80ea0bd0edcbe67273de368836 ] When dump_one_state() returns an error, e.g. because of a too small buffer to dump the whole xfrm state, xfrm_state_netlink() returns NULL instead of an error pointer. But its callers expect an error pointer and therefore continue to operate on a NULL skbuff. This could lead to a privilege escalation (execution of user code in kernel context) if the attacker has CAP_NET_ADMIN and is able to map address 0. Signed-off-by: Mathias Krause Acked-by: Steffen Klassert Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- net/xfrm/xfrm_user.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index 7cae73e..a092828 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -862,6 +862,7 @@ static struct sk_buff *xfrm_state_netlink(struct sk_buff *in_skb, { struct xfrm_dump_info info; struct sk_buff *skb; + int err; skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); if (!skb) @@ -872,9 +873,10 @@ static struct sk_buff *xfrm_state_netlink(struct sk_buff *in_skb, info.nlmsg_seq = seq; info.nlmsg_flags = 0; - if (dump_one_state(x, 0, &info)) { + err = dump_one_state(x, 0, &info); + if (err) { kfree_skb(skb); - return NULL; + return ERR_PTR(err); } return skb; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/