[PATCH] HID: pidff: Fix integer overflow in pidff_rescale

[Tomasz Pakuła]

Rescaling values close to the max (U16_MAX) temporairly creates values
that exceed the s32 range. This caused value overflow in case when, for
example, a periodic effect phase was higher than 180 degrees. In turn,
rescale function could return values outside of the logical range of the
HID field (negative when logical minimum is 0).

Fix by using 64 bit signed integer to store the value during calculation
but still return only 32 bit integer.

Closes: https://github.com/JacKeTUs/universal-pidff/issues/116
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Tomasz Pakuła <tomasz.pakula.oficjalny@xxxxxxxxx>
---
For inclusion in the 7.1-RC period

 drivers/hid/usbhid/hid-pidff.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/usbhid/hid-pidff.c b/drivers/hid/usbhid/hid-pidff.c
index aee8a4443305..fb9b4f292732 100644
--- a/drivers/hid/usbhid/hid-pidff.c
+++ b/drivers/hid/usbhid/hid-pidff.c
@@ -326,8 +326,9 @@ static s32 pidff_clamp(s32 i, struct hid_field *field)
  */
 static int pidff_rescale(int i, int max, struct hid_field *field)
 {
-	return i * (field->logical_maximum - field->logical_minimum) / max +
-	       field->logical_minimum;
+	/* 64 bits needed for big values during rescale */
+	return (s64)i * (field->logical_maximum - field->logical_minimum) /
+		max + field->logical_minimum;
 }
 
 /*
-- 
2.53.0