[PATCH v3] net: usb: usbnet: update __usbnet_{read|write}_cmd() to use new API

From: Anant Thazhemadam
Date: Sat Oct 31 2020 - 17:35:42 EST


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@xxxxxxxxx>
---
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