netdev - [PATCH] xfrm_user: return error pointer instead of NULL #2

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Date:	Fri, 14 Sep 2012 21:58:32 +0200
From:	Mathias Krause <minipli@...glemail.com>
To:	"David S. Miller" <davem@...emloft.net>
Cc:	Steffen Klassert <steffen.klassert@...unet.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Mathias Krause <minipli@...glemail.com>, stable@...r.kernel.org
Subject: [PATCH] xfrm_user: return error pointer instead of NULL #2

When dump_one_policy() returns an error, e.g. because of a too small
buffer to dump the whole xfrm policy, xfrm_policy_netlink() returns
NULL instead of an error pointer. But its caller expects an error
pointer and therefore continues to operate on a NULL skbuff.

Cc: stable@...r.kernel.org
Signed-off-by: Mathias Krause <minipli@...glemail.com>
---

Note, this is a different, but similar issue as my previous patch
with the almost same subject.

I'm not aware of a way how to exploit this bug as the policy *should*
always fit into the netlink buffer but better safe then sorry, so cc
stable.

 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 dac08e2..d12b625 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1548,6 +1548,7 @@ static struct sk_buff *xfrm_policy_netlink(struct sk_buff *in_skb,
 {
 	struct xfrm_dump_info info;
 	struct sk_buff *skb;
+	int err;
 
 	skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 	if (!skb)
@@ -1558,9 +1559,10 @@ static struct sk_buff *xfrm_policy_netlink(struct sk_buff *in_skb,
 	info.nlmsg_seq = seq;
 	info.nlmsg_flags = 0;
 
-	if (dump_one_policy(xp, dir, 0, &info) < 0) {
+	err = dump_one_policy(xp, dir, 0, &info);
+	if (err) {
 		kfree_skb(skb);
-		return NULL;
+		return ERR_PTR(err);
 	}
 
 	return skb;
-- 
1.7.10.4

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