mm: sharepool: check size=0 in mg_sp_make_share_k2u()

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5QQPG
CVE: NA

--------------------------------

Add a size-0-check in mg_sp_make_share_k2u() to avoid passing 0-size spa
to __insert_sp_area().
Signed-off-by: NGuo Mengqi <guomengqi3@huawei.com>
Reviewed-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

mm/share_pool.c

@@ -3097,6 +3097,11 @@ static int sp_k2u_prepare(unsigned long kva, unsigned long size,
 
 	trace_sp_k2u_begin(kc);
 
+	if (!size) {
+		pr_err_ratelimited("k2u input size is 0.\n");
+		return -EINVAL;
+	}
+
 	if (sp_flags & ~SP_FLAG_MASK) {
 		pr_err_ratelimited("k2u sp_flags %lx error\n", sp_flags);
 		return -EINVAL;