Commit 864745d2 authored Sep 13, 2012 by Mathias Krause Committed by David S. Miller Sep 18, 2012

xfrm_user: return error pointer instead of NULL



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 <minipli@googlemail.com>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 2c20cbd7

net/xfrm/xfrm_user.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -878,6 +878,7 @@ 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)
		@@ -888,9 +889,10 @@ 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;

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