wifi: rtlwifi: fix incorrect error codes in rtl_debugfs_set_write_reg()

[ Upstream commit 5dbe1f8eb8c5ac69394400a5b86fd81775e96c43 ]

If there is a failure during copy_from_user or user-provided data buffer is
invalid, rtl_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.

Fixes: 610247f46feb ("rtlwifi: Improve debugging by using debugfs")
Signed-off-by: Wei Chen <harperchen1110@gmail.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230326054217.93492-1-harperchen1110@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/wireless/realtek/rtlwifi/debug.c b/drivers/net/wireless/realtek/rtlwifi/debug.c
index 6027179..9eb26df 100644 (file)
--- a/drivers/net/wireless/realtek/rtlwifi/debug.c
+++ b/drivers/net/wireless/realtek/rtlwifi/debug.c
@@ -278,8 +278,8 @@ static ssize_t rtl_debugfs_set_write_reg(struct file *filp,
 
        tmp_len = (count > sizeof(tmp) - 1 ? sizeof(tmp) - 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';
 
@@ -287,7 +287,7 @@ static ssize_t rtl_debugfs_set_write_reg(struct file *filp,
        num = sscanf(tmp, "%x %x %x", &addr, &val, &len);
 
        if (num !=  3)
-               return count;
+               return -EINVAL;
 
        switch (len) {
        case 1: