[PATCH 4/4] mm/msync: return EINVAL for illegal user memory range for msync

[Wupeng Ma <mawupeng1@xxxxxxxxxx>]

From: Ma Wupeng <mawupeng1@xxxxxxxxxx>

Add access_ok to check user memory range and return EINVAL if overflows for
msync.

Signed-off-by: Ma Wupeng <mawupeng1@xxxxxxxxxx>
---
 mm/msync.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/msync.c b/mm/msync.c
index ac4c9bfea2e7..a87c3dca473a 100644
--- a/mm/msync.c
+++ b/mm/msync.c
@@ -43,6 +43,8 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags)
 		goto out;
 	if (offset_in_page(start))
 		goto out;
+	if (unlikely(!access_ok((void __user *)start, len)))
+		goto out;
 	if ((flags & MS_ASYNC) && (flags & MS_SYNC))
 		goto out;
 	error = -ENOMEM;
-- 
2.25.1