2023-05-09 04:32:56

by Dmitry Torokhov

[permalink] [raw]
Subject: [PATCH] Input: psmouse - fix OOB access in Elantech protocol

The kernel only allocate 5 MT slots; check that transmitted slot ID
falls within the acceptable range.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=217417
Signed-off-by: Dmitry Torokhov <[email protected]>
---
drivers/input/mouse/elantech.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index ece97f8c6a3e..2118b2075f43 100644
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c
@@ -674,10 +674,11 @@ static void process_packet_head_v4(struct psmouse *psmouse)
struct input_dev *dev = psmouse->dev;
struct elantech_data *etd = psmouse->private;
unsigned char *packet = psmouse->packet;
- int id = ((packet[3] & 0xe0) >> 5) - 1;
+ int id;
int pres, traces;

- if (id < 0)
+ id = ((packet[3] & 0xe0) >> 5) - 1;
+ if (id < 0 || id >= ETP_MAX_FINGERS)
return;

etd->mt[id].x = ((packet[1] & 0x0f) << 8) | packet[2];
@@ -707,7 +708,7 @@ static void process_packet_motion_v4(struct psmouse *psmouse)
int id, sid;

id = ((packet[0] & 0xe0) >> 5) - 1;
- if (id < 0)
+ if (id < 0 || id >= ETP_MAX_FINGERS)
return;

sid = ((packet[3] & 0xe0) >> 5) - 1;
@@ -728,7 +729,7 @@ static void process_packet_motion_v4(struct psmouse *psmouse)
input_report_abs(dev, ABS_MT_POSITION_X, etd->mt[id].x);
input_report_abs(dev, ABS_MT_POSITION_Y, etd->mt[id].y);

- if (sid >= 0) {
+ if (sid >= 0 && sid < ETP_MAX_FINGERS) {
etd->mt[sid].x += delta_x2 * weight;
etd->mt[sid].y -= delta_y2 * weight;
input_mt_slot(dev, sid);
--
2.40.1.521.gf1e218fcd8-goog


--
Dmitry