[PATCH v3 4/4] mm/msync: return ENOMEM if len overflows for msync

[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 -ENOMEM if len overflows for msync.

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

diff --git a/mm/msync.c b/mm/msync.c
index ac4c9bfea2e7..3104c97d70d3 100644
--- a/mm/msync.c
+++ b/mm/msync.c
@@ -46,13 +46,16 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags)
 	if ((flags & MS_ASYNC) && (flags & MS_SYNC))
 		goto out;
 	error = -ENOMEM;
+	if (!len)
+		return 0;
+
 	len = (len + ~PAGE_MASK) & PAGE_MASK;
+	if (!len)
+		goto out;
+
 	end = start + len;
 	if (end < start)
 		goto out;
-	error = 0;
-	if (end == start)
-		goto out;
 	/*
 	 * If the interval [start,end) covers some unmapped address ranges,
 	 * just ignore them, but return -ENOMEM at the end. Besides, if the
-- 
2.25.1