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authorClaudia Pellegrino <linux@cpellegrino.de>2021-11-14 03:53:27 +0100
committerJiri Kosina <jkosina@suse.cz>2021-11-19 15:54:31 +0100
commita1091118e0d6d84c2fdb94e6c397ac790bfb9dd6 (patch)
tree9f3f93d948edcac6eca7a968a4e66c07fae53acb /drivers/hid
parentfa48020c9fae2872f7bf8f38e09f73eb61fdb4ce (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>
Diffstat (limited to 'drivers/hid')
-rw-r--r--drivers/hid/hid-magicmouse.c7
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;