diff options
| author | Claudia Pellegrino <linux@cpellegrino.de> | 2021-11-14 03:53:27 +0100 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2021-11-19 15:54:31 +0100 |
| commit | a1091118e0d6d84c2fdb94e6c397ac790bfb9dd6 (patch) | |
| tree | 9f3f93d948edcac6eca7a968a4e66c07fae53acb | |
| parent | fa48020c9fae2872f7bf8f38e09f73eb61fdb4ce (diff) | |
HID: magicmouse: prevent division by 0 on scroll
In hid_magicmouse, if the user has set scroll_speed to a value between
55 and 63 and scrolls seven times in quick succession, the
step_hr variable in the magicmouse_emit_touch function becomes 0.
That causes a division by zero further down in the function when
it does `step_x_hr /= step_hr`.
To reproduce, create `/etc/modprobe.d/hid_magicmouse.conf` with the
following content:
```
options hid_magicmouse scroll_acceleration=1 scroll_speed=55
```
Then reboot, connect a Magic Mouse and scroll seven times quickly.
The system will freeze for a minute, and after that `dmesg` will
confirm that a division by zero occurred.
Enforce a minimum of 1 for the variable so the high resolution
step count can never reach 0 even at maximum scroll acceleration.
Fixes: d4b9f10a0eb6 ("HID: magicmouse: enable high-resolution scroll")
Signed-off-by: Claudia Pellegrino <linux@cpellegrino.de>
Tested-by: José Expósito <jose.exposito89@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
| -rw-r--r-- | drivers/hid/hid-magicmouse.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/hid/hid-magicmouse.c b/drivers/hid/hid-magicmouse.c index 686788ebf3e1..d7687ce70614 100644 --- a/drivers/hid/hid-magicmouse.c +++ b/drivers/hid/hid-magicmouse.c @@ -256,8 +256,11 @@ static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tda unsigned long now = jiffies; int step_x = msc->touches[id].scroll_x - x; int step_y = msc->touches[id].scroll_y - y; - int step_hr = ((64 - (int)scroll_speed) * msc->scroll_accel) / - SCROLL_HR_STEPS; + int step_hr = + max_t(int, + ((64 - (int)scroll_speed) * msc->scroll_accel) / + SCROLL_HR_STEPS, + 1); int step_x_hr = msc->touches[id].scroll_x_hr - x; int step_y_hr = msc->touches[id].scroll_y_hr - y; |