[PATCH v2 2/4] HID: core: introduce hid_safe_input_report()

[Benjamin Tissoires <bentiss@kernel.org>]

hid_input_report() is used in too many places to have a commit that
doesn't cross subsystem borders. Instead of changing the API, introduce
a new one when things matters in the transport layers:
- usbhid
- i2chid

This effectively revert to the old behavior for those two transport
layers.

Fixes: 0a3fe972a7cb ("HID: core: Mitigate potential OOB by removing bogus memset()")
Cc: stable@vger.kernel.org
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
---
 drivers/hid/hid-core.c             | 25 +++++++++++++++++++++++++
 drivers/hid/i2c-hid/i2c-hid-core.c |  7 ++++---
 drivers/hid/usbhid/hid-core.c      | 11 ++++++-----
 include/linux/hid.h                |  2 ++
 4 files changed, 37 insertions(+), 8 deletions(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index a806820df7e5..b3596851c719 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2181,6 +2181,7 @@ static int __hid_input_report(struct hid_device *hid, enum hid_report_type type,
  * @interrupt: distinguish between interrupt and control transfers
  *
  * This is data entry for lower layers.
+ * Legacy, please use hid_safe_input_report() instead.
  */
 int hid_input_report(struct hid_device *hid, enum hid_report_type type, u8 *data, u32 size,
 		     int interrupt)
@@ -2191,6 +2192,30 @@ int hid_input_report(struct hid_device *hid, enum hid_report_type type, u8 *data
 }
 EXPORT_SYMBOL_GPL(hid_input_report);
 
+/**
+ * hid_safe_input_report - report data from lower layer (usb, bt...)
+ *
+ * @hid: hid device
+ * @type: HID report type (HID_*_REPORT)
+ * @data: report contents
+ * @bufsize: allocated size of the data buffer
+ * @size: useful size of data parameter
+ * @interrupt: distinguish between interrupt and control transfers
+ *
+ * This is data entry for lower layers.
+ * Please use this function instead of the non safe version because we provide
+ * here the size of the buffer, allowing hid-core to make smarter decisions
+ * regarding the incoming buffer.
+ */
+int hid_safe_input_report(struct hid_device *hid, enum hid_report_type type, u8 *data,
+			  size_t bufsize, u32 size, int interrupt)
+{
+	return __hid_input_report(hid, type, data, bufsize, size, interrupt, 0,
+				  false, /* from_bpf */
+				  false /* lock_already_taken */);
+}
+EXPORT_SYMBOL_GPL(hid_safe_input_report);
+
 bool hid_match_one_id(const struct hid_device *hdev,
 		      const struct hid_device_id *id)
 {
diff --git a/drivers/hid/i2c-hid/i2c-hid-core.c b/drivers/hid/i2c-hid/i2c-hid-core.c
index 5a183af3d5c6..e0a302544cef 100644
--- a/drivers/hid/i2c-hid/i2c-hid-core.c
+++ b/drivers/hid/i2c-hid/i2c-hid-core.c
@@ -574,9 +574,10 @@ static void i2c_hid_get_input(struct i2c_hid *ihid)
 		if (ihid->hid->group != HID_GROUP_RMI)
 			pm_wakeup_event(&ihid->client->dev, 0);
 
-		hid_input_report(ihid->hid, HID_INPUT_REPORT,
-				ihid->inbuf + sizeof(__le16),
-				ret_size - sizeof(__le16), 1);
+		hid_safe_input_report(ihid->hid, HID_INPUT_REPORT,
+				      ihid->inbuf + sizeof(__le16),
+				      ihid->bufsize - sizeof(__le16),
+				      ret_size - sizeof(__le16), 1);
 	}
 
 	return;
diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
index fbbfc0f60829..5af93b9b1fb5 100644
--- a/drivers/hid/usbhid/hid-core.c
+++ b/drivers/hid/usbhid/hid-core.c
@@ -283,9 +283,9 @@ static void hid_irq_in(struct urb *urb)
 			break;
 		usbhid_mark_busy(usbhid);
 		if (!test_bit(HID_RESUME_RUNNING, &usbhid->iofl)) {
-			hid_input_report(urb->context, HID_INPUT_REPORT,
-					 urb->transfer_buffer,
-					 urb->actual_length, 1);
+			hid_safe_input_report(urb->context, HID_INPUT_REPORT,
+					      urb->transfer_buffer, urb->transfer_buffer_length,
+					      urb->actual_length, 1);
 			/*
 			 * autosuspend refused while keys are pressed
 			 * because most keyboards don't wake up when
@@ -482,9 +482,10 @@ static void hid_ctrl(struct urb *urb)
 	switch (status) {
 	case 0:			/* success */
 		if (usbhid->ctrl[usbhid->ctrltail].dir == USB_DIR_IN)
-			hid_input_report(urb->context,
+			hid_safe_input_report(urb->context,
 				usbhid->ctrl[usbhid->ctrltail].report->type,
-				urb->transfer_buffer, urb->actual_length, 0);
+				urb->transfer_buffer, urb->transfer_buffer_length,
+				urb->actual_length, 0);
 		break;
 	case -ESHUTDOWN:	/* unplug */
 		unplug = 1;
diff --git a/include/linux/hid.h b/include/linux/hid.h
index ac432a2ef415..bfb9859f391e 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -1030,6 +1030,8 @@ struct hid_field *hid_find_field(struct hid_device *hdev, unsigned int report_ty
 int hid_set_field(struct hid_field *, unsigned, __s32);
 int hid_input_report(struct hid_device *hid, enum hid_report_type type, u8 *data, u32 size,
 		     int interrupt);
+int hid_safe_input_report(struct hid_device *hid, enum hid_report_type type, u8 *data,
+			  size_t bufsize, u32 size, int interrupt);
 struct hid_field *hidinput_get_led_field(struct hid_device *hid);
 unsigned int hidinput_count_leds(struct hid_device *hid);
 __s32 hidinput_calc_abs_res(const struct hid_field *field, __u16 code);

-- 
2.53.0