Re: [PATCH net 1/2] openvswitch: check for null return for nla_nest_start

The call to nla_nest_start in conntrack can lead to a NULL
return so it's possible for attr to become NULL and we can potentially
get a NULL pointer dereference on attr.  Fix this by checking for
a NULL return.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=200533
Fixes: 11efd5cb04a1 ("openvswitch: Support conntrack zone limit")
Signed-off-by: Stephen Hemminger <redacted>
---
 net/openvswitch/conntrack.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
index 284aca2a252d..2e316f641df8 100644
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c

@@ -2132,6 +2132,8 @@ static int ovs_ct_limit_cmd_get(struct sk_buff *skb, struct genl_info *info)
                return PTR_ERR(reply);

        nla_reply = nla_nest_start(reply, OVS_CT_LIMIT_ATTR_ZONE_LIMIT);
+       if (!nla_reply)
+               return PRT_ERR(-EMSGSIZE);

        if (a[OVS_CT_LIMIT_ATTR_ZONE_LIMIT]) {
                err = ovs_ct_limit_get_zone_limit(
--