Commit 74c16618 authored by Joe Stringer's avatar Joe Stringer Committed by David S. Miller
Browse files

openvswitch: Fix double-free on ip_defrag() errors 



If ip_defrag() returns an error other than -EINPROGRESS, then the skb is
freed. When handle_fragments() passes this back up to
do_execute_actions(), it will be freed again. Prevent this double free
by never freeing the skb in do_execute_actions() for errors returned by
ovs_ct_execute. Always free it in ovs_ct_execute() error paths instead.

Fixes: 7f8a436e ("openvswitch: Add conntrack action")
Reported-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarJoe Stringer <joestringer@nicira.com>
Acked-by: default avatarPravin B Shelar <pshelar@nicira.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c2229fe1

net/openvswitch/actions.c

+2 −2
Original line number Diff line number Diff line
@@ -1109,8 +1109,8 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb, 
					     nla_data(a));



			/* Hide stolen IP fragments from user space. */

			if (err == -EINPROGRESS)

				return 0;

			if (err)

				return err == -EINPROGRESS ? 0 : err;

			break;

		}

net/openvswitch/conntrack.c

+13 −4
Original line number Diff line number Diff line
@@ -293,6 +293,9 @@ static int ovs_ct_helper(struct sk_buff *skb, u16 proto) 
	return helper->help(skb, protoff, ct, ctinfo);

}



/* Returns 0 on success, -EINPROGRESS if 'skb' is stolen, or other nonzero

 * value if 'skb' is freed.

 */

static int handle_fragments(struct net *net, struct sw_flow_key *key,

			    u16 zone, struct sk_buff *skb)

{
@@ -308,8 +311,8 @@ static int handle_fragments(struct net *net, struct sw_flow_key *key, 
			return err;



		ovs_cb.mru = IPCB(skb)->frag_max_size;

	} else if (key->eth.type == htons(ETH_P_IPV6)) {

#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)

	} else if (key->eth.type == htons(ETH_P_IPV6)) {

		enum ip6_defrag_users user = IP6_DEFRAG_CONNTRACK_IN + zone;

		struct sk_buff *reasm;
@@ -318,17 +321,18 @@ static int handle_fragments(struct net *net, struct sw_flow_key *key, 
		if (!reasm)

			return -EINPROGRESS;



		if (skb == reasm)

		if (skb == reasm) {

			kfree_skb(skb);

			return -EINVAL;

		}



		key->ip.proto = ipv6_hdr(reasm)->nexthdr;

		skb_morph(skb, reasm);

		consume_skb(reasm);

		ovs_cb.mru = IP6CB(skb)->frag_max_size;

#else

		return -EPFNOSUPPORT;

#endif

	} else {

		kfree_skb(skb);

		return -EPFNOSUPPORT;

	}
@@ -473,6 +477,9 @@ static bool labels_nonzero(const struct ovs_key_ct_labels *labels) 
	return false;

}



/* Returns 0 on success, -EINPROGRESS if 'skb' is stolen, or other nonzero

 * value if 'skb' is freed.

 */

int ovs_ct_execute(struct net *net, struct sk_buff *skb,

		   struct sw_flow_key *key,

		   const struct ovs_conntrack_info *info)
@@ -508,6 +515,8 @@ int ovs_ct_execute(struct net *net, struct sk_buff *skb, 
					&info->labels.mask);

err:

	skb_push(skb, nh_ofs);

	if (err)

		kfree_skb(skb);

	return err;

}

net/openvswitch/conntrack.h

+1 −0
Original line number Diff line number Diff line
@@ -67,6 +67,7 @@ static inline int ovs_ct_execute(struct net *net, struct sk_buff *skb, 
				 struct sw_flow_key *key,

				 const struct ovs_conntrack_info *info)

{

	kfree_skb(skb);

	return -ENOTSUPP;

}

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