Date:   Mon, 13 Dec 2021 16:01:46 +0100
Message-Id: <20211213150146.4000441-1-glider@google.com>
Mime-Version: 1.0
Subject: [PATCH v2] Input: psmouse: check the result of ps2_command() when
 detecting devices
From:   Alexander Potapenko <glider@google.com>
To:     dmitry.torokhov@gmail.com
Cc:     dvyukov@google.com, elver@google.com, linux-input@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Alexander Potapenko <glider@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Execution of ps2_command() may fail, leaving the device in inconsistent
state. If the command was supposed to write into @param buffer, that one
may remain uninitialized.

Ensure that ps2_command() failure in device detection functions also
results in them returning an error.

Signed-off-by: Alexander Potapenko <glider@google.com>
---
v2:
 - add checking to PSMOUSE_CMD_SET* functions
---
 drivers/input/mouse/psmouse-base.c | 73 ++++++++++++++++++++++--------
 1 file changed, 55 insertions(+), 18 deletions(-)

diff --git a/drivers/input/mouse/psmouse-base.c b/drivers/input/mouse/psmouse-base.c
index 0b4a3039f312f..9dde7fd818136 100644
--- a/drivers/input/mouse/psmouse-base.c
+++ b/drivers/input/mouse/psmouse-base.c
@@ -546,13 +546,24 @@ static int genius_detect(struct psmouse *psmouse, bool set_properties)
 {
 	struct ps2dev *ps2dev = &psmouse->ps2dev;
 	u8 param[4];
+	int error;
 
 	param[0] = 3;
-	ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES);
-	ps2_command(ps2dev,  NULL, PSMOUSE_CMD_SETSCALE11);
-	ps2_command(ps2dev,  NULL, PSMOUSE_CMD_SETSCALE11);
-	ps2_command(ps2dev,  NULL, PSMOUSE_CMD_SETSCALE11);
-	ps2_command(ps2dev, param, PSMOUSE_CMD_GETINFO);
+	error = ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES);
+	if (error)
+		return error;
+	error = ps2_command(ps2dev,  NULL, PSMOUSE_CMD_SETSCALE11);
+	if (error)
+		return error;
+	error = ps2_command(ps2dev,  NULL, PSMOUSE_CMD_SETSCALE11);
+	if (error)
+		return error;
+	error = ps2_command(ps2dev,  NULL, PSMOUSE_CMD_SETSCALE11);
+	if (error)
+		return error;
+	error = ps2_command(ps2dev, param, PSMOUSE_CMD_GETINFO);
+	if (error)
+		return error;
 
 	if (param[0] != 0x00 || param[1] != 0x33 || param[2] != 0x55)
 		return -ENODEV;
@@ -578,14 +589,23 @@ static int intellimouse_detect(struct psmouse *psmouse, bool set_properties)
 {
 	struct ps2dev *ps2dev = &psmouse->ps2dev;
 	u8 param[2];
+	int error;
 
 	param[0] = 200;
-	ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
+	error = ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
+	if (error)
+		return error;
 	param[0] = 100;
-	ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
+	error = ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
+	if (error)
+		return error;
 	param[0] =  80;
-	ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
-	ps2_command(ps2dev, param, PSMOUSE_CMD_GETID);
+	error = ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
+	if (error)
+		return error;
+	error = ps2_command(ps2dev, param, PSMOUSE_CMD_GETID);
+	if (error)
+		return error;
 
 	if (param[0] != 3)
 		return -ENODEV;
@@ -611,16 +631,25 @@ static int im_explorer_detect(struct psmouse *psmouse, bool set_properties)
 {
 	struct ps2dev *ps2dev = &psmouse->ps2dev;
 	u8 param[2];
+	int error;
 
 	intellimouse_detect(psmouse, 0);
 
 	param[0] = 200;
-	ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
+	error = ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
+	if (error)
+		return error;
 	param[0] = 200;
-	ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
+	error = ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
+	if (error)
+		return error;
 	param[0] =  80;
-	ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
-	ps2_command(ps2dev, param, PSMOUSE_CMD_GETID);
+	error = ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
+	if (error)
+		return error;
+	error = ps2_command(ps2dev, param, PSMOUSE_CMD_GETID);
+	if (error)
+		return error;
 
 	if (param[0] != 4)
 		return -ENODEV;
@@ -658,17 +687,25 @@ static int thinking_detect(struct psmouse *psmouse, bool set_properties)
 	struct ps2dev *ps2dev = &psmouse->ps2dev;
 	u8 param[2];
 	static const u8 seq[] = { 20, 60, 40, 20, 20, 60, 40, 20, 20 };
-	int i;
+	int error, i;
 
 	param[0] = 10;
-	ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
+	error = ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
+	if (error)
+		return error;
 	param[0] = 0;
-	ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES);
+	error = ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES);
+	if (error)
+		return error;
 	for (i = 0; i < ARRAY_SIZE(seq); i++) {
 		param[0] = seq[i];
-		ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
+		error = ps2_command(ps2dev, param, PSMOUSE_CMD_SETRATE);
+		if (error)
+			return error;
 	}
-	ps2_command(ps2dev, param, PSMOUSE_CMD_GETID);
+	error = ps2_command(ps2dev, param, PSMOUSE_CMD_GETID);
+	if (error)
+		return error;
 
 	if (param[0] != 2)
 		return -ENODEV;
-- 
2.34.1.173.g76aa8bc2d0-goog