V4L/DVB (12755): af9015: improve usb control message function slightly

* define names for few values
* decrease buffer len by one byte which was not used
* add check for buffer overflow for sure
* indentation fixes
* remove useless 0 len check from memcpy
It should not happen and if it happens memcpy should not do anything.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 24 insertions, 8 deletions

diff --git a/drivers/media/dvb/dvb-usb/af9015.c b/drivers/media/dvb/dvb-usb/af9015.c
index fdfa0f54291c..ebb9981eb89e 100644
--- a/drivers/media/dvb/dvb-usb/af9015.c
+++ b/drivers/media/dvb/dvb-usb/af9015.c
@@ -61,10 +61,13 @@ static struct af9013_config af9015_af9013_config[] = {
 
 static int af9015_rw_udev(struct usb_device *udev, struct req_t *req)
 {
+#define BUF_LEN 63
+#define REQ_HDR_LEN 8 /* send header size */
+#define ACK_HDR_LEN 2 /* rece header size */
         int act_len, ret;
-        u8 buf[64];
+        u8 buf[BUF_LEN];
         u8 write = 1;
-        u8 msg_len = 8;
+        u8 msg_len = REQ_HDR_LEN;
         static u8 seq; /* packet sequence number */
 
         if (mutex_lock_interruptible(&af9015_usb_mutex) < 0)
@@ -107,17 +110,26 @@ static int af9015_rw_udev(struct usb_device *udev, struct req_t *req)
                 goto error_unlock;
         }
 
+        /* buffer overflow check */
+        if ((write && (req->data_len > BUF_LEN - REQ_HDR_LEN)) ||
+                (!write && (req->data_len > BUF_LEN - ACK_HDR_LEN))) {
+                err("too much data; cmd:%d len:%d", req->cmd, req->data_len);
+                ret = -EINVAL;
+                goto error_unlock;
+        }
+
         /* write requested */
         if (write) {
-                memcpy(&buf[8], req->data, req->data_len);
+                memcpy(&buf[REQ_HDR_LEN], req->data, req->data_len);
                 msg_len += req->data_len;
         }
+
         deb_xfer(">>> ");
         debug_dump(buf, msg_len, deb_xfer);
 
         /* send req */
         ret = usb_bulk_msg(udev, usb_sndbulkpipe(udev, 0x02), buf, msg_len,
-        &act_len, AF9015_USB_TIMEOUT);
+                &act_len, AF9015_USB_TIMEOUT);
         if (ret)
                 err("bulk message failed:%d (%d/%d)", ret, msg_len, act_len);
         else
@@ -130,10 +142,14 @@ static int af9015_rw_udev(struct usb_device *udev, struct req_t *req)
         if (req->cmd == DOWNLOAD_FIRMWARE || req->cmd == RECONNECT_USB)
                 goto exit_unlock;
 
-        /* receive ack and data if read req */
-        msg_len = 1 + 1 + req->data_len;  /* seq + status + data len */
+        /* write receives seq + status = 2 bytes
+           read receives seq + status + data = 2 + N bytes */
+        msg_len = ACK_HDR_LEN;
+        if (!write)
+                msg_len += req->data_len;
+
         ret = usb_bulk_msg(udev, usb_rcvbulkpipe(udev, 0x81), buf, msg_len,
-                           &act_len, AF9015_USB_TIMEOUT);
+                &act_len, AF9015_USB_TIMEOUT);
         if (ret) {
                 err("recv bulk message failed:%d", ret);
                 ret = -1;
@@ -159,7 +175,7 @@ static int af9015_rw_udev(struct usb_device *udev, struct req_t *req)
 
         /* read request, copy returned data to return buf */
         if (!write)
-                memcpy(req->data, &buf[2], req->data_len);
+                memcpy(req->data, &buf[ACK_HDR_LEN], req->data_len);
 
 error_unlock:
 exit_unlock: