[PATCH 01/10] wifi: rtw88: fix incorrect error codes in rtw_debugfs_set_write_reg

[Zhang Shurong]

If there is a failure during copy_from_user or user-provided data
buffer is invalid, rtw_debugfs_set_write_reg should return negative
error code instead of a positive value count.

Fix this bug by returning correct error code. Moreover, the check
of buffer against null is removed since it will be handled by
copy_from_user.

Signed-off-by: Zhang Shurong <zhang_shurong@xxxxxxxxxxx>
---
 drivers/net/wireless/realtek/rtw88/debug.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw88/debug.c b/drivers/net/wireless/realtek/rtw88/debug.c
index fa3d73b333ba..bc41c5a7acaf 100644
--- a/drivers/net/wireless/realtek/rtw88/debug.c
+++ b/drivers/net/wireless/realtek/rtw88/debug.c
@@ -183,8 +183,8 @@ static int rtw_debugfs_copy_from_user(char tmp[], int size,
 
 	tmp_len = (count > size - 1 ? size - 1 : count);
 
-	if (!buffer || copy_from_user(tmp, buffer, tmp_len))
-		return count;
+	if (copy_from_user(tmp, buffer, tmp_len))
+		return -EFAULT;
 
 	tmp[tmp_len] = '\0';
 
@@ -338,14 +338,17 @@ static ssize_t rtw_debugfs_set_write_reg(struct file *filp,
 	char tmp[32 + 1];
 	u32 addr, val, len;
 	int num;
+	int ret;
 
-	rtw_debugfs_copy_from_user(tmp, sizeof(tmp), buffer, count, 3);
+	ret = rtw_debugfs_copy_from_user(tmp, sizeof(tmp), buffer, count, 3);
+	if (ret < 0)
+		return ret;
 
 	/* write BB/MAC register */
 	num = sscanf(tmp, "%x %x %x", &addr, &val, &len);
 
 	if (num !=  3)
-		return count;
+		return -EINVAL;
 
 	switch (len) {
 	case 1:
-- 
2.40.0