linux-kernel - [PATCH 4.14 127/176] Input: joydev - prevent potential read overflow in ioctl

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Message-Id: <20210301161027.295902515@linuxfoundation.org>
Date:   Mon,  1 Mar 2021 17:13:20 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>
Subject: [PATCH 4.14 127/176] Input: joydev - prevent potential read overflow in ioctl

From: Dan Carpenter <dan.carpenter@...cle.com>

commit 182d679b2298d62bf42bb14b12a8067b8e17b617 upstream.

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@...cle.com>
Link: https://lore.kernel.org/r/YCyzR8WvFRw4HWw6@mwanda
[dtor: additional check for len being even in joydev_handle_JSIOCSBTNMAP]
Cc: stable@...r.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/input/joydev.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/drivers/input/joydev.c
+++ b/drivers/input/joydev.c
@@ -460,7 +460,7 @@ static int joydev_handle_JSIOCSAXMAP(str
 	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;
@@ -484,6 +484,9 @@ static int joydev_handle_JSIOCSBTNMAP(st
 	int i;
 	int retval = 0;
 
+	if (len % sizeof(*keypam))
+		return -EINVAL;
+
 	len = min(len, sizeof(joydev->keypam));
 
 	/* Validate the map. */
@@ -491,7 +494,7 @@ static int joydev_handle_JSIOCSBTNMAP(st
 	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;