HID: stop exporting hid_snto32()

jira LE-4395
cve CVE-2025-38556
Rebuild_History Non-Buildable kernel-6.12.0-55.39.1.el10_0
commit-author Dmitry Torokhov <dmitry.torokhov@gmail.com>
commit c653ffc

The only user of hid_snto32() is Logitech HID++ driver, which always
calls hid_snto32() with valid size (constant, either 12 or 8) and
therefore can simply use sign_extend32().

Make the switch and remove hid_snto32(). Move snto32() and s32ton() to
avoid introducing forward declaration.

	Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Link: https://patch.msgid.link/20241003144656.3786064-2-dmitry.torokhov@gmail.com
[bentiss: fix checkpatch warning]
	Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
(cherry picked from commit c653ffc)
	Signed-off-by: Jonathan Maple <jmaple@ciq.com>

Author: PlaidCat

drivers/hid/hid-core.c

@@ -45,6 +45,34 @@ static int hid_ignore_special_drivers = 0;
 module_param_named(ignore_special_drivers, hid_ignore_special_drivers, int, 0600);
 MODULE_PARM_DESC(ignore_special_drivers, "Ignore any special drivers and handle all devices by generic driver");
 
+/*
+ * Convert a signed n-bit integer to signed 32-bit integer.
+ */
+
+static s32 snto32(__u32 value, unsigned int n)
+{
+	if (!value || !n)
+		return 0;
+
+	if (n > 32)
+		n = 32;
+
+	return sign_extend32(value, n - 1);
+}
+
+/*
+ * Convert a signed 32-bit integer to a signed n-bit integer.
+ */
+
+static u32 s32ton(__s32 value, unsigned int n)
+{
+	s32 a = value >> (n - 1);
+
+	if (a && a != -1)
+		return value < 0 ? 1 << (n - 1) : (1 << (n - 1)) - 1;
+	return value & ((1 << n) - 1);
+}
+
 /*
  * Register a new report for a device.
  */
@@ -425,7 +453,7 @@ static int hid_parser_global(struct hid_parser *parser, struct hid_item *item)
 		 * both this and the standard encoding. */
 		raw_value = item_sdata(item);
 		if (!(raw_value & 0xfffffff0))
-			parser->global.unit_exponent = hid_snto32(raw_value, 4);
+			parser->global.unit_exponent = snto32(raw_value, 4);
 		else
 			parser->global.unit_exponent = raw_value;
 		return 0;
@@ -1315,39 +1343,6 @@ int hid_open_report(struct hid_device *device)
 }
 EXPORT_SYMBOL_GPL(hid_open_report);
 
-/*
- * Convert a signed n-bit integer to signed 32-bit integer.
- */
-
-static s32 snto32(__u32 value, unsigned n)
-{
-	if (!value || !n)
-		return 0;
-
-	if (n > 32)
-		n = 32;
-
-	return sign_extend32(value, n - 1);
-}
-
-s32 hid_snto32(__u32 value, unsigned n)
-{
-	return snto32(value, n);
-}
-EXPORT_SYMBOL_GPL(hid_snto32);
-
-/*
- * Convert a signed 32-bit integer to a signed n-bit integer.
- */
-
-static u32 s32ton(__s32 value, unsigned n)
-{
-	s32 a = value >> (n - 1);
-	if (a && a != -1)
-		return value < 0 ? 1 << (n - 1) : (1 << (n - 1)) - 1;
-	return value & ((1 << n) - 1);
-}
-
 /*
  * Extract/implement a data field from/to a little endian report (bit array).
  *

drivers/hid/hid-logitech-hidpp.c

@@ -3296,13 +3296,13 @@ static int m560_raw_event(struct hid_device *hdev, u8 *data, int size)
 					 120);
 		}
 
-		v = hid_snto32(hid_field_extract(hdev, data+3, 0, 12), 12);
+		v = sign_extend32(hid_field_extract(hdev, data + 3, 0, 12), 11);
 		input_report_rel(hidpp->input, REL_X, v);
 
-		v = hid_snto32(hid_field_extract(hdev, data+3, 12, 12), 12);
+		v = sign_extend32(hid_field_extract(hdev, data + 3, 12, 12), 11);
 		input_report_rel(hidpp->input, REL_Y, v);
 
-		v = hid_snto32(data[6], 8);
+		v = sign_extend32(data[6], 7);
 		if (v != 0)
 			hidpp_scroll_counter_handle_scroll(hidpp->input,
 					&hidpp->vertical_wheel_counter, v);

include/linux/hid.h

@@ -974,7 +974,6 @@ const struct hid_device_id *hid_match_device(struct hid_device *hdev,
 					     struct hid_driver *hdrv);
 bool hid_compare_device_paths(struct hid_device *hdev_a,
 			      struct hid_device *hdev_b, char separator);
-s32 hid_snto32(__u32 value, unsigned n);
 __u32 hid_field_extract(const struct hid_device *hid, __u8 *report,
 		     unsigned offset, unsigned n);