net: openvswitch: fix nested key length validation in the set() action

It's not safe to access nla_len(ovs_key) if the data is smaller than
the netlink header.  Check that the attribute is OK first.

Fixes: ccb1352e76cf ("net: Add Open vSwitch kernel components.")
Reported-by: syzbot+b07a9da40df1576b8048@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=b07a9da40df1576b8048
Tested-by: syzbot+b07a9da40df1576b8048@syzkaller.appspotmail.com
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
Reviewed-by: Eelco Chaudron <echaudro@redhat.com>
Acked-by: Aaron Conole <aconole@redhat.com>
Link: https://patch.msgid.link/20250412104052.2073688-1-i.maximets@ovn.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
index 95e0dd14dc1a32add3b48c136831a433de5aea09..518be23e48ea934d77dbc129d7be6c9a52f9702d 100644 (file)
--- a/net/openvswitch/flow_netlink.c
+++ b/net/openvswitch/flow_netlink.c
@@ -2876,7 +2876,8 @@ static int validate_set(const struct nlattr *a,
        size_t key_len;
 
        /* There can be only one key in a action */
-       if (nla_total_size(nla_len(ovs_key)) != nla_len(a))
+       if (!nla_ok(ovs_key, nla_len(a)) ||
+           nla_total_size(nla_len(ovs_key)) != nla_len(a))
                return -EINVAL;
 
        key_len = nla_len(ovs_key);