[PATCH v2] HID: pidff: Fix integer overflow in pidff_rescale

["Tomasz Pakuła" <tomasz.pakula.oficjalny@gmail.com>]

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

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
Fixes: 224ee88fe395 ("Input: add force feedback driver for PID devices")
Cc: <stable@vger.kernel.org>
Signed-off-by: Tomasz Pakuła <tomasz.pakula.oficjalny@gmail.com>
---
For inclusion in 7.1 RC period.

v2: use div_s64() instead of plain division

 drivers/hid/usbhid/hid-pidff.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/usbhid/hid-pidff.c b/drivers/hid/usbhid/hid-pidff.c
index aee8a4443305..c45f182d0448 100644
--- a/drivers/hid/usbhid/hid-pidff.c
+++ b/drivers/hid/usbhid/hid-pidff.c
@@ -11,6 +11,7 @@
 #include "hid-pidff.h"
 #include <linux/hid.h>
 #include <linux/input.h>
+#include <linux/math64.h>
 #include <linux/minmax.h>
 #include <linux/slab.h>
 #include <linux/stringify.h>
@@ -326,8 +327,10 @@ 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 */
+	s64 result = field->logical_maximum - field->logical_minimum;
+
+	return div_s64(result * i, max) + field->logical_minimum;
 }
 
 /*
-- 
2.54.0