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: 7f8a436eaa2c ("openvswitch: Add conntrack action")
Reported-by: Florian Westphal <f...@strlen.de>
Signed-off-by: Joe Stringer <joestrin...@nicira.com>
---
v2: Remove extraneous whitespace change.
v3: Push skb before checking error to free
---
net/openvswitch/actions.c | 4 ++--
net/openvswitch/conntrack.c | 17 +++++++++++++----
net/openvswitch/conntrack.h | 1 +
3 files changed, 16 insertions(+), 6 deletions(-)
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 0bf0f406de52..dba635d086b2 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -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;
}
diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
index a5ec34f8502f..b5dcc0abde66 100644
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -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;
}
diff --git a/net/openvswitch/conntrack.h b/net/openvswitch/conntrack.h
index 82e0dfc66028..a7544f405c16 100644
--- a/net/openvswitch/conntrack.h
+++ b/net/openvswitch/conntrack.h
@@ -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;
}
--
2.1.4
--
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