From: Mathias Krause Date: Thu, 13 Sep 2012 11:41:26 +0000 (+0000) Subject: xfrm_user: return error pointer instead of NULL X-Git-Tag: v3.5.7~106 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b2b4b6e0f57ca9aac148e67f351ab8f34a9a1272;p=thirdparty%2Fkernel%2Fstable.git xfrm_user: return error pointer instead of NULL [ 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: Greg Kroah-Hartman --- diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index 44293b3fd6a1d..d9d4f637cafec 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -872,6 +872,7 @@ 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) @@ -882,9 +883,10 @@ 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;