[PATCH v4 3/4] mm/mempolicy: return EINVAL if len overflows for mbind

[Wupeng Ma]

From: Ma Wupeng <mawupeng1@xxxxxxxxxx>

Return -EINVAL if len overflows for mbind.

Signed-off-by: Ma Wupeng <mawupeng1@xxxxxxxxxx>
---
 mm/mempolicy.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 3a68998adc3a..6b1c45021e48 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1259,6 +1259,7 @@ static long do_mbind(unsigned long start, unsigned long len,
 		     nodemask_t *nmask, unsigned long flags)
 {
 	struct mm_struct *mm = current->mm;
+	unsigned long old_len = len;
 	struct mempolicy *new;
 	unsigned long end;
 	int err;
@@ -1279,7 +1280,7 @@ static long do_mbind(unsigned long start, unsigned long len,
 	len = PAGE_ALIGN(len);
 	end = start + len;
 
-	if (end < start)
+	if (end < start || (old_len != 0 && len == 0))
 		return -EINVAL;
 	if (end == start)
 		return 0;
-- 
2.25.1