netdev - [PATCH v3] net: usb: usbnet: update __usbnet_{read|write}

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Message-Id: <20201031213533.40829-1-anant.thazhemadam@gmail.com>
Date:   Sun,  1 Nov 2020 03:05:33 +0530
From:   Anant Thazhemadam <anant.thazhemadam@...il.com>
To:     Oliver Neukum <oneukum@...e.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        Anant Thazhemadam <anant.thazhemadam@...il.com>
Subject: [PATCH v3] net: usb: usbnet: update __usbnet_{read|write}_cmd() to use new API

Currently, __usbnet_{read|write}_cmd() use usb_control_msg().
However, this could lead to potential partial reads/writes being
considered valid, and since most of the callers of
usbnet_{read|write}_cmd() don't take partial reads/writes into account
(only checking for negative error number is done), and this can lead to
issues.

However, the new usb_control_msg_{send|recv}() APIs don't allow partial
reads and writes.
Using the new APIs also relaxes the return value checking that must
be done after usbnet_{read|write}_cmd() is called.

Signed-off-by: Anant Thazhemadam <anant.thazhemadam@...il.com>
---
Changes in v3:
	* Aligned continuation lines after the opening brackets
Changes in v2:
	* Fix build error

 drivers/net/usb/usbnet.c | 52 ++++++++--------------------------------
 1 file changed, 10 insertions(+), 42 deletions(-)

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index bf6c58240bd4..b2df3417a41c 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1982,64 +1982,32 @@ EXPORT_SYMBOL(usbnet_link_change);
 static int __usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
 			     u16 value, u16 index, void *data, u16 size)
 {
-	void *buf = NULL;
-	int err = -ENOMEM;
 
 	netdev_dbg(dev->net, "usbnet_read_cmd cmd=0x%02x reqtype=%02x"
 		   " value=0x%04x index=0x%04x size=%d\n",
 		   cmd, reqtype, value, index, size);
 
-	if (size) {
-		buf = kmalloc(size, GFP_KERNEL);
-		if (!buf)
-			goto out;
-	}
-
-	err = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0),
-			      cmd, reqtype, value, index, buf, size,
-			      USB_CTRL_GET_TIMEOUT);
-	if (err > 0 && err <= size) {
-        if (data)
-            memcpy(data, buf, err);
-        else
-            netdev_dbg(dev->net,
-                "Huh? Data requested but thrown away.\n");
-    }
-	kfree(buf);
-out:
-	return err;
+	return usb_control_msg_recv(dev->udev, 0,
+				    cmd, reqtype, value, index, data, size,
+				    USB_CTRL_GET_TIMEOUT, GFP_KERNEL);
 }
 
 static int __usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
 			      u16 value, u16 index, const void *data,
 			      u16 size)
 {
-	void *buf = NULL;
-	int err = -ENOMEM;
-
 	netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
 		   " value=0x%04x index=0x%04x size=%d\n",
 		   cmd, reqtype, value, index, size);
 
-	if (data) {
-		buf = kmemdup(data, size, GFP_KERNEL);
-		if (!buf)
-			goto out;
-	} else {
-        if (size) {
-            WARN_ON_ONCE(1);
-            err = -EINVAL;
-            goto out;
-        }
-    }
-
-	err = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
-			      cmd, reqtype, value, index, buf, size,
-			      USB_CTRL_SET_TIMEOUT);
-	kfree(buf);
+	if (size && !data) {
+		WARN_ON_ONCE(1);
+		return -EINVAL;
+	}
 
-out:
-	return err;
+	return usb_control_msg_send(dev->udev, 0,
+				    cmd, reqtype, value, index, data, size,
+				    USB_CTRL_SET_TIMEOUT, GFP_KERNEL);
 }
 
 /*
-- 
2.25.1