[PATCH] Input: joydev - prevent potential read overflow in ioctl

[Dan Carpenter <dan.carpenter@oracle.com>]

The problem here is that "len" might be less than "joydev->nabs" so the
loops which verfy abspam[i] and keypam[] might read beyond the buffer.

Fixes: 999b874f4aa3 ("Input: joydev - validate axis/button maps before clobbering current ones")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/input/joydev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/input/joydev.c b/drivers/input/joydev.c
index a2b5fbba2d3b..750f4513fe20 100644
--- a/drivers/input/joydev.c
+++ b/drivers/input/joydev.c
@@ -456,7 +456,7 @@ static int joydev_handle_JSIOCSAXMAP(struct joydev *joydev,
 	if (IS_ERR(abspam))
 		return PTR_ERR(abspam);
 
-	for (i = 0; i < joydev->nabs; i++) {
+	for (i = 0; i < len && i < joydev->nabs; i++) {
 		if (abspam[i] > ABS_MAX) {
 			retval = -EINVAL;
 			goto out;
@@ -487,7 +487,7 @@ static int joydev_handle_JSIOCSBTNMAP(struct joydev *joydev,
 	if (IS_ERR(keypam))
 		return PTR_ERR(keypam);
 
-	for (i = 0; i < joydev->nkey; i++) {
+	for (i = 0; i < (len / 2) && i < joydev->nkey; i++) {
 		if (keypam[i] > KEY_MAX || keypam[i] < BTN_MISC) {
 			retval = -EINVAL;
 			goto out;
-- 
2.30.0