[PATCH 3/4] mm/mempolicy: return EINVAL for illegal user memory range for mbind

[Wupeng Ma <mawupeng1@xxxxxxxxxx>]

From: Ma Wupeng <mawupeng1@xxxxxxxxxx>

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

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

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index e3a2c465fe8a..a6bddf454953 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1272,6 +1272,9 @@ static long do_mbind(unsigned long start, unsigned long len,
 	if (start & ~PAGE_MASK)
 		return -EINVAL;
 
+	if (unlikely(!access_ok((void __user *)start, len)))
+		return -EINVAL;
+
 	if (mode == MPOL_DEFAULT)
 		flags &= ~MPOL_MF_STRICT;
 
-- 
2.25.1