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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dan Carpenter <dan.carpenter@oracle.com>,
        Kalle Valo <kvalo@kernel.org>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 069/287] wifi: rtlwifi: fix error codes in rtl_debugfs_set_write_h2c()
Date:   Tue, 23 Aug 2022 10:23:58 +0200
Message-Id: <20220823080102.558731356@linuxfoundation.org>
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From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit b88d28146c30a8e14f0f012d56ebf19b68a348f4 ]

If the copy_from_user() fails or the user gives invalid date then the
correct thing to do is to return a negative error code.  (Currently it
returns success).

I made a copy additional related cleanups:
1) There is no need to check "buffer" for NULL.  That's handled by
copy_from_user().
2) The "h2c_len" variable cannot be negative because it is unsigned
and because sscanf() does not return negative error codes.

Fixes: 610247f46feb ("rtlwifi: Improve debugging by using debugfs")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/YoOLnDkHgVltyXK7@kili
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/wireless/realtek/rtlwifi/debug.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtlwifi/debug.c b/drivers/net/wireless/realtek/rtlwifi/debug.c
index 498994041bbc..474439fc2da1 100644
--- a/drivers/net/wireless/realtek/rtlwifi/debug.c
+++ b/drivers/net/wireless/realtek/rtlwifi/debug.c
@@ -370,8 +370,8 @@ static ssize_t rtl_debugfs_set_write_h2c(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';
 
@@ -381,8 +381,8 @@ static ssize_t rtl_debugfs_set_write_h2c(struct file *filp,
 			 &h2c_data[4], &h2c_data[5],
 			 &h2c_data[6], &h2c_data[7]);
 
-	if (h2c_len <= 0)
-		return count;
+	if (h2c_len == 0)
+		return -EINVAL;
 
 	for (i = 0; i < h2c_len; i++)
 		h2c_data_packed[i] = (u8)h2c_data[i];
-- 
2.35.1