net: rtnetlink: fix module reference count leak issue in rtnetlink_rcv_msg

When bulk delete command is received in the rtnetlink_rcv_msg function,
if bulk delete is not supported, module_put is not called to release
the reference counting. As a result, module reference count is leaked.

Fixes: a6cec0bcd3 ("net: rtnetlink: add bulk delete support flag")
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://lore.kernel.org/r/20220815024629.240367-1-shaozhengchao@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/core/rtnetlink.c

@@ -6070,6 +6070,7 @@ static int rtnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (kind == RTNL_KIND_DEL && (nlh->nlmsg_flags & NLM_F_BULK) &&
 	    !(flags & RTNL_FLAG_BULK_DEL_SUPPORTED)) {
 		NL_SET_ERR_MSG(extack, "Bulk delete is not supported");
+		module_put(owner);
 		goto err_unlock;
 	}