linux-kernel - [PATCH] HID: wacom: avoid integer overflow in wacom_intuos

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Message-ID: <20230417160148.60011-1-n.zhandarovich@fintech.ru>
Date:   Mon, 17 Apr 2023 09:01:48 -0700
From:   Nikita Zhandarovich <n.zhandarovich@...tech.ru>
To:     Ping Cheng <ping.cheng@...om.com>
CC:     Nikita Zhandarovich <n.zhandarovich@...tech.ru>,
        Jason Gerecke <jason.gerecke@...om.com>,
        Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        <linux-input@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <lvc-project@...uxtesting.org>
Subject: [PATCH] HID: wacom: avoid integer overflow in wacom_intuos_inout()

If high bit is set to 1 in ((data[3] & 0x0f << 28), after all arithmetic
operations and integer promotions are done, high bits in
wacom->serial[idx] will be filled with 1s as well.
Avoid this, albeit unlikely, issue by specifying left operand's __u64
type for the right operand.

Found by Linux Verification Center (linuxtesting.org) with static
analysis tool SVACE.

Fixes: 3bea733ab212 ("USB: wacom tablet driver reorganization")
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@...tech.ru>
---
 drivers/hid/wacom_wac.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index 9312d611db8e..0e4404f3801e 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -826,7 +826,7 @@ static int wacom_intuos_inout(struct wacom_wac *wacom)
 	/* Enter report */
 	if ((data[1] & 0xfc) == 0xc0) {
 		/* serial number of the tool */
-		wacom->serial[idx] = ((data[3] & 0x0f) << 28) +
+		wacom->serial[idx] = ((__u64)(data[3] & 0x0f) << 28) +
 			(data[4] << 20) + (data[5] << 12) +
 			(data[6] << 4) + (data[7] >> 4);
 
-- 
2.25.1