[PATCH] HID: ft260: improve error handling of ft260_hid_feature_report_get()

From: trix
Date: Fri May 07 2021 - 14:38:10 EST


From: Tom Rix <trix@xxxxxxxxxx>

Static analysis reports this representative problem

hid-ft260.c:787:9: warning: 4th function call argument is an
uninitialized value
return scnprintf(buf, PAGE_SIZE, "%hi\n", *field);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Uses of ft260_hid_feature_report_get() check 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.

Fixes: 6a82582d9fa4 ("HID: ft260: add usb hid to i2c host bridge driver")
Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
---
drivers/hid/hid-ft260.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c
index 7a9ba984a75a..628fa664a10b 100644
--- a/drivers/hid/hid-ft260.c
+++ b/drivers/hid/hid-ft260.c
@@ -249,7 +249,8 @@ 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 (ret == len)
+ memcpy(data, buf, len);
kfree(buf);
return ret;
}
@@ -295,12 +296,16 @@ static int ft260_xfer_status(struct ft260_device *dev)
struct hid_device *hdev = dev->hdev;
struct ft260_get_i2c_status_report report;
int ret;
+ int len = sizeof(report);

ret = ft260_hid_feature_report_get(hdev, FT260_I2C_STATUS,
- (u8 *)&report, sizeof(report));
- if (ret < 0) {
+ (u8 *)&report, len);
+ if (ret != len) {
hid_err(hdev, "failed to retrieve status: %d\n", ret);
- return ret;
+ if (ret >= 0)
+ return -EIO;
+ else
+ return ret;
}

dev->clock = le16_to_cpu(report.clock);
@@ -728,6 +733,8 @@ static int ft260_get_system_config(struct hid_device *hdev,
hid_err(hdev, "failed to retrieve system status\n");
if (ret >= 0)
return -EIO;
+ else
+ return ret;
}
return 0;
}
@@ -782,6 +789,8 @@ static int ft260_byte_show(struct hid_device *hdev, int id, u8 *cfg, int len,
ret = ft260_hid_feature_report_get(hdev, id, cfg, len);
if (ret != len && ret >= 0)
return -EIO;
+ else if (ret < 0)
+ return ret;

return scnprintf(buf, PAGE_SIZE, "%hi\n", *field);
}
@@ -794,6 +803,8 @@ static int ft260_word_show(struct hid_device *hdev, int id, u8 *cfg, int len,
ret = ft260_hid_feature_report_get(hdev, id, cfg, len);
if (ret != len && ret >= 0)
return -EIO;
+ else if (ret < 0)
+ return ret;

return scnprintf(buf, PAGE_SIZE, "%hi\n", le16_to_cpu(*field));
}
--
2.26.3