On Tue, May 11, 2021 at 06:10:36AM -0700, Tom Rix wrote:

Generally change is fine.

a nit below.

On 5/11/21 3:12 AM, Michael Zaidman wrote:

quoted

Fixes: 6a82582d9fa4 ("HID: ft260: add usb hid to i2c host bridge driver")

The ft260_hid_feature_report_get() checks if the return size matches
the requested size. But the function can also fail with at least -ENOMEM.
Add the < 0 checks.

In ft260_hid_feature_report_get(), do not do the memcpy to the caller's
buffer if there is an error.

---
v4   Fixed commit message
---
v3   Simplify and optimize the changes
---
v2:  add unlikely()'s for error conditions
---

Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Michael Zaidman <michael.zaidman@gmail.com>
---
  drivers/hid/hid-ft260.c | 24 ++++++++++++------------
  1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c
index 047aa85a7c83..7f4cb823129e 100644
--- a/drivers/hid/hid-ft260.c
+++ b/drivers/hid/hid-ft260.c

@@ -249,7 +249,10 @@ static int ft260_hid_feature_report_get(struct hid_device *hdev,
  	ret = hid_hw_raw_request(hdev, report_id, buf, len, HID_FEATURE_REPORT,
  				 HID_REQ_GET_REPORT);
-	memcpy(data, buf, len);
+	if (likely(ret == len))
+		memcpy(data, buf, len);
+	else if (ret >= 0)
+		ret = -EIO;
  	kfree(buf);
  	return ret;
  }

@@ -298,7 +301,7 @@ static int ft260_xfer_status(struct ft260_device *dev)
  	ret = ft260_hid_feature_report_get(hdev, FT260_I2C_STATUS,
  					   (u8 *)&report, sizeof(report));
-	if (ret < 0) {
+	if (unlikely(ret < 0)) {
  		hid_err(hdev, "failed to retrieve status: %d\n", ret);
  		return ret;
  	}

@@ -720,10 +723,9 @@ static int ft260_get_system_config(struct hid_device *hdev,
  	ret = ft260_hid_feature_report_get(hdev, FT260_SYSTEM_SETTINGS,
  					   (u8 *)cfg, len);
-	if (ret != len) {
+	if (ret < 0) {

nit: should be consistent and use unlikely(ret < 0) for this and other
similar checks.

Tom

I preserved the likely/unlikely hints in the critical path where the
performance matters. And for the sake of consistency, I removed them from
the rest of the places that are called rarely and are not performance-critical
to be aligned to the other "if" statements in the code.

Michael