!1461 [sync] PR-1425: loop: loop_set_status_from_info() check before assignment

Merge Pull Request from: @openeuler-sync-bot 
 

Origin pull request: 
https://gitee.com/openeuler/kernel/pulls/1425 
 
PR sync from: Zhong Jinghua <zhongjinghua@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/3G4GOSWGIMJSHVPDQ6QC6X64RMPRIJIW/ 
 
https://gitee.com/openeuler/kernel/issues/I7JHOA 
 
Link:https://gitee.com/openeuler/kernel/pulls/1461 

Reviewed-by: Yu Kuai <yukuai3@huawei.com> 
Reviewed-by: Jialin Zhang <zhangjialin11@huawei.com> 
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> 

drivers/block/loop.c

@@ -1029,13 +1029,13 @@ loop_set_status_from_info(struct loop_device *lo,
 	if (err)
 		return err;
 
+	/* Avoid assigning overflow values */
+	if (info->lo_offset > LLONG_MAX || info->lo_sizelimit > LLONG_MAX)
+		return -EOVERFLOW;
+
 	lo->lo_offset = info->lo_offset;
 	lo->lo_sizelimit = info->lo_sizelimit;
 
-	/* loff_t vars have been assigned __u64 */
-	if (lo->lo_offset < 0 || lo->lo_sizelimit < 0)
-		return -EOVERFLOW;
-
 	memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
 	memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
 	lo->lo_file_name[LO_NAME_SIZE-1] = 0;