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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>
This commit is contained in:
Mathias Krause 2012-09-13 11:41:26 +00:00 committed by David S. Miller
parent 2c20cbd7e3
commit 864745d291
1 changed files with 4 additions and 2 deletions
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6
net/xfrm/xfrm_user.c
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@ -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;