[PATCH] usbnet: make sure no NULL pointer is passed through

[PATCH] usbnet: make sure no NULL pointer is passed through

[Oliver Neukum]

Coverity reports:

** CID 751368:  Null pointer dereferences  (FORWARD_NULL)
/drivers/net/usb/usbnet.c: 1925 in __usbnet_read_cmd()

________________________________________________________________________________________________________
*** CID 751368:  Null pointer dereferences  (FORWARD_NULL)
/drivers/net/usb/usbnet.c: 1925 in __usbnet_read_cmd()
1919     EXPORT_SYMBOL(usbnet_link_change);
1920
1921     /*-------------------------------------------------------------------------*/
1922     static int __usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1923                                 u16 value, u16 index, void *data, u16 size)
1924     {
>>>     CID 751368:  Null pointer dereferences  (FORWARD_NULL)
>>>     Assigning: "buf" = "NULL".
1925            void *buf = NULL;
1926            int err = -ENOMEM;
1927
1928            netdev_dbg(dev->net, "usbnet_read_cmd cmd=0x%02x reqtype=%02x"
1929                       " value=0x%04x index=0x%04x size=%d\n",
1930                       cmd, reqtype, value, index, size);

** CID 751370:  Null pointer dereferences  (FORWARD_NULL)
/drivers/net/usb/usbnet.c: 1952 in __usbnet_write_cmd()

________________________________________________________________________________________________________
*** CID 751370:  Null pointer dereferences  (FORWARD_NULL)
/drivers/net/usb/usbnet.c: 1952 in __usbnet_write_cmd()
1946     }
1947
1948     static int __usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
1949                                  u16 value, u16 index, const void *data,
1950                                  u16 size)
1951     {
>>>     CID 751370:  Null pointer dereferences  (FORWARD_NULL)
>>>     Assigning: "buf" = "NULL".
1952            void *buf = NULL;
1953            int err = -ENOMEM;
1954
1955            netdev_dbg(dev->net, "usbnet_write_cmd cmd=0x%02x reqtype=%02x"
1956                       " value=0x%04x index=0x%04x size=%d\n",
1957                       cmd, reqtype, value, index, size);

** CID 1325026:  Null pointer dereferences  (FORWARD_NULL)
/drivers/net/usb/ch9200.c: 143 in control_write()

It is valid to offer commands without a buffer, but then you need a size
of zero. This should actually be checked.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/net/usb/usbnet.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 3de65ea..4532448 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1929,7 +1929,7 @@ static int __usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
 		   " value=0x%04x index=0x%04x size=%d\n",
 		   cmd, reqtype, value, index, size);
 
-	if (data) {
+	if (size) {
 		buf = kmalloc(size, GFP_KERNEL);
 		if (!buf)
 			goto out;
@@ -1938,8 +1938,13 @@ static int __usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
 	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)
-		memcpy(data, buf, err);
+	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;
@@ -1960,7 +1965,13 @@ static int __usbnet_write_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
 		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,
-- 
2.10.2

Re: [PATCH] usbnet: make sure no NULL pointer is passed through

[David Miller]

From: Oliver Neukum <oneukum@suse.com>
Date: Wed,  5 Apr 2017 14:14:39 +0200

> Coverity reports:
 ...
> It is valid to offer commands without a buffer, but then you need a size
> of zero. This should actually be checked.
> 
> Signed-off-by: Oliver Neukum <oneukum@suse.com>

Applied, thanks Oliver.

I had to apply this by hand via my inbox rather than using patchwork
because those coverity report delimiters cause patchwork to chop off
most of your commit message.

Just FYI...

Re: [PATCH] usbnet: make sure no NULL pointer is passed through

[Oliver Neukum]

Am Donnerstag, den 06.04.2017, 13:19 -0700 schrieb David Miller:
> From: Oliver Neukum <oneukum@suse.com>
> Date: Wed,  5 Apr 2017 14:14:39 +0200
> 
> > Coverity reports:
>  ...
> > It is valid to offer commands without a buffer, but then you need a size
> > of zero. This should actually be checked.
> > 
> > Signed-off-by: Oliver Neukum <oneukum@suse.com>
> 
> Applied, thanks Oliver.
> 
> I had to apply this by hand via my inbox rather than using patchwork
> because those coverity report delimiters cause patchwork to chop off
> most of your commit message.
> 

Hi,

thanks. That is not good. It seems to me that a Coverity report
should be in the change log. Do you have suggestions how to do
this in a friendly manner?

	Regards
		Oliver