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: sta...@vger.kernel.org
Signed-off-by: Mathias Krause <mini...@googlemail.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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