[PATCH synaptics] eventcomm: prevent possibly division by zero

[Peter Hutterer]

This came up as a kernel bug, but it's valid to create uinput devices with a
min == max range for x/y. Technically valid, but effectively useless, so catch
it, complain and hobble on along.

Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
---
 src/eventcomm.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/eventcomm.c b/src/eventcomm.c
index 53a0ca4..cddf7fc 100644
--- a/src/eventcomm.c
+++ b/src/eventcomm.c
@@ -436,6 +436,11 @@ event_query_axis_ranges(InputInfoPtr pInfo)
     event_get_abs(proto_data->evdev, ABS_Y, &priv->miny, &priv->maxy,
                   &priv->synpara.hyst_y, &priv->resy);
 
+    if (priv->minx == priv->maxx || priv->miny == priv->maxy) {
+        xf86IDrvMsg(pInfo, X_ERROR, "Kernel bug: min == max on ABS_X/Y\n");
+        return;
+    }
+
     priv->has_pressure = libevdev_has_event_code(proto_data->evdev, EV_ABS, ABS_PRESSURE);
     priv->has_width = libevdev_has_event_code(proto_data->evdev, EV_ABS, ABS_TOOL_WIDTH);
 
@@ -458,6 +463,11 @@ event_query_axis_ranges(InputInfoPtr pInfo)
         event_get_abs(proto_data->evdev, ABS_MT_POSITION_Y, &priv->miny,
                       &priv->maxy, &priv->synpara.hyst_y, &priv->resy);
 
+        if (priv->minx == priv->maxx || priv->miny == priv->maxy) {
+            xf86IDrvMsg(pInfo, X_ERROR, "Kernel bug: min == max on ABS_MT_POSITION_X/Y\n");
+            return;
+        }
+
         proto_data->st_to_mt_offset[0] = priv->minx - st_minx;
         proto_data->st_to_mt_scale[0] =
             (priv->maxx - priv->minx) / (st_maxx - st_minx);
-- 
2.3.2