[PATCH v3 1/2] wifi: rtw88: fix incorrect error codes in rtw_debugfs_copy_from_user

[Zhang Shurong <zhang_shurong@foxmail.com>]

If there is a failure during copy_from_user or user-provided data
buffer is invalid, rtw_debugfs_copy_from_user 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@foxmail.com>
---
 drivers/net/wireless/realtek/rtw88/debug.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw88/debug.c b/drivers/net/wireless/realtek/rtw88/debug.c
index fa3d73b333ba..3da477e1ebd3 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';
 
-- 
2.40.0