| From bc7ec91718c49d938849697cfad98fcd9877cc26 Mon Sep 17 00:00:00 2001 |
| From: "Leo L. Schwab" <ewhac@ewhac.org> |
| Date: Thu, 30 Dec 2021 21:05:00 -0800 |
| Subject: Input: spaceball - fix parsing of movement data packets |
| |
| From: Leo L. Schwab <ewhac@ewhac.org> |
| |
| 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 <ewhac@ewhac.org> |
| Link: https://lore.kernel.org/r/20211221101630.1146385-1-ewhac@ewhac.org |
| Cc: stable@vger.kernel.org |
| Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| drivers/input/joystick/spaceball.c | 11 +++++++++-- |
| 1 file changed, 9 insertions(+), 2 deletions(-) |
| |
| --- a/drivers/input/joystick/spaceball.c |
| +++ b/drivers/input/joystick/spaceball.c |
| @@ -31,6 +31,7 @@ |
| #include <linux/module.h> |
| #include <linux/input.h> |
| #include <linux/serio.h> |
| +#include <asm/unaligned.h> |
| |
| #define DRIVER_DESC "SpaceTec SpaceBall 2003/3003/4000 FLX driver" |
| |
| @@ -87,9 +88,15 @@ static void spaceball_process_packet(str |
| |
| 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 */ |
