[PATCH v3 2/4] mm/mempolicy: return EINVAL for if len overflows for set_mempolicy_home_node

[Wupeng Ma <mawupeng1@huawei.com>]

From: Ma Wupeng <mawupeng1@huawei.com>

Check and return 0 if len == 0 at the beginning of the function.
Return -EINVAL if len overflows for set_mempolicy_home_node.

Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
---
 mm/mempolicy.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 02c8a712282f..85c5d3c2503b 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1512,13 +1512,16 @@ SYSCALL_DEFINE4(set_mempolicy_home_node, unsigned long, start, unsigned long, le
 	if (home_node >= MAX_NUMNODES || !node_online(home_node))
 		return -EINVAL;
 
+	if (!len)
+		return 0;
+
 	len = PAGE_ALIGN(len);
-	end = start + len;
+	if (!len)
+		return -EINVAL;
 
+	end = start + len;
 	if (end < start)
 		return -EINVAL;
-	if (end == start)
-		return 0;
 	mmap_write_lock(mm);
 	for_each_vma_range(vmi, vma, end) {
 		vmstart = max(start, vma->vm_start);
-- 
2.25.1