From: Bryam Vargas Date: Sat, 13 Jun 2026 02:10:33 +0000 (-0500) Subject: Input: goodix - clamp the device-reported contact count X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5ed62a96e06be4e94b8296b7932afee550a70e04;p=thirdparty%2Flinux.git Input: goodix - clamp the device-reported contact count goodix_ts_read_input_report() copies the number of touch points reported by the device into an on-stack buffer u8 point_data[2 + GOODIX_MAX_CONTACT_SIZE * GOODIX_MAX_CONTACTS]; which is sized for at most GOODIX_MAX_CONTACTS (10) contacts. The only runtime check bounds the per-interrupt count against ts->max_touch_num, but that value is taken verbatim from a 4-bit field of the device configuration block and is never clamped: ts->max_touch_num = ts->config[MAX_CONTACTS_LOC] & 0x0f; The nibble can be 0..15, so a malfunctioning, malicious or counterfeit controller (or an attacker tampering with the I2C bus) can advertise up to 15 contacts. goodix_ts_read_input_report() then accepts a touch_num of up to 15 and the second goodix_i2c_read() writes ts->contact_size * (touch_num - 1) bytes past the one-contact header into point_data - up to 30 bytes (45 with the 9-byte report format) beyond the 92-byte buffer: a stack out-of-bounds write. Clamp max_touch_num to GOODIX_MAX_CONTACTS, the number of contacts point_data[] is sized for, when reading it from the configuration. Fixes: a7ac7c95d468 ("Input: goodix - use max touch number from device config") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Reviewed-by: Hans de Goede Link: https://patch.msgid.link/20260612-b4-disp-6844625d-v1-1-df0aed080c9d@proton.me Signed-off-by: Dmitry Torokhov --- diff --git a/drivers/input/touchscreen/goodix.c b/drivers/input/touchscreen/goodix.c index 2c48ad8ee2e6..03efc0c792c2 100644 --- a/drivers/input/touchscreen/goodix.c +++ b/drivers/input/touchscreen/goodix.c @@ -1057,7 +1057,8 @@ static void goodix_read_config(struct goodix_ts_data *ts) } ts->int_trigger_type = ts->config[TRIGGER_LOC] & 0x03; - ts->max_touch_num = ts->config[MAX_CONTACTS_LOC] & 0x0f; + ts->max_touch_num = min(ts->config[MAX_CONTACTS_LOC] & 0x0f, + GOODIX_MAX_CONTACTS); x_max = get_unaligned_le16(&ts->config[RESOLUTION_LOC]); y_max = get_unaligned_le16(&ts->config[RESOLUTION_LOC + 2]);