cifsd: fix memory leak when loop ends

mainline inclusion
from mainline-5.15-rc1
commit c250e8f5
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I60T7G
CVE: NA

Reference: https://git.kernel.org/torvalds/linux/c/c250e8f5566f

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

Memory is being allocated and if veto_list is zero, the loop breaks
without cleaning up the allocated memory. In this patch, the length
check has been moved before allocation. If loop breaks, the memory isn't
allocated in the first place. Thus the memory is being protected from
leaking.
Reported-by: Ncoverity-bot <keescook+coverity-bot@chromium.org>
Addresses-Coverity-ID: 1503590 ("Resource leaks")
Signed-off-by: NMuhammad Usama Anjum <musamaanjum@gmail.com>
Signed-off-by: NNamjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>
Signed-off-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NZhong Jinghua <zhongjinghua@huawei.com>

fs/cifsd/mgmt/share_config.c

@@ -92,14 +92,14 @@ static int parse_veto_list(struct ksmbd_share_config *share,
 	while (veto_list_sz > 0) {
 		struct ksmbd_veto_pattern *p;
 
-		p = kzalloc(sizeof(struct ksmbd_veto_pattern), GFP_KERNEL);
-		if (!p)
-			return -ENOMEM;
-
 		sz = strlen(veto_list);
 		if (!sz)
 			break;
 
+		p = kzalloc(sizeof(struct ksmbd_veto_pattern), GFP_KERNEL);
+		if (!p)
+			return -ENOMEM;
+
 		p->pattern = kstrdup(veto_list, GFP_KERNEL);
 		if (!p->pattern) {
 			ksmbd_free(p);