From 466267ced87dd514fc0f64e477c3ef5bb881d4f3 Mon Sep 17 00:00:00 2001 From: "Leo L. Schwab" Date: Thu, 30 Dec 2021 21:05:00 -0800 Subject: [PATCH] Input: spaceball - fix parsing of movement data packets commit bc7ec91718c49d938849697cfad98fcd9877cc26 upstream. The spaceball.c module was not properly parsing the movement reports coming from the device. The code read axis data as signed 16-bit little-endian values starting at offset 2. In fact, axis data in Spaceball movement reports are signed 16-bit big-endian values starting at offset 3. This was determined first by visually inspecting the data packets, and later verified by consulting: http://spacemice.org/pdf/SpaceBall_2003-3003_Protocol.pdf If this ever worked properly, it was in the time before Git... Signed-off-by: Leo L. Schwab Link: https://lore.kernel.org/r/20211221101630.1146385-1-ewhac@ewhac.org Cc: stable@vger.kernel.org Signed-off-by: Dmitry Torokhov Signed-off-by: Greg Kroah-Hartman --- drivers/input/joystick/spaceball.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/input/joystick/spaceball.c b/drivers/input/joystick/spaceball.c index 429411c..a85a4f3 100644 --- a/drivers/input/joystick/spaceball.c +++ b/drivers/input/joystick/spaceball.c @@ -19,6 +19,7 @@ #include #include #include +#include #define DRIVER_DESC "SpaceTec SpaceBall 2003/3003/4000 FLX driver" @@ -75,9 +76,15 @@ static void spaceball_process_packet(struct spaceball* spaceball) case 'D': /* Ball data */ if (spaceball->idx != 15) return; - for (i = 0; i < 6; i++) + /* + * Skip first three bytes; read six axes worth of data. + * Axis values are signed 16-bit big-endian. + */ + data += 3; + for (i = 0; i < ARRAY_SIZE(spaceball_axes); i++) { input_report_abs(dev, spaceball_axes[i], - (__s16)((data[2 * i + 3] << 8) | data[2 * i + 2])); + (__s16)get_unaligned_be16(&data[i * 2])); + } break; case 'K': /* Button data */ -- 2.7.4