qmi_wwan: add support for QMAP padding in the RX path

The QMAP code in the qmi_wwan driver is based on the CodeAurora GobiNet
driver which does not process QMAP padding in the RX path correctly.
Add support for QMAP padding to qmimux_rx_fixup() according to the
description of the rmnet driver.

Fixes: c6adf77953bc ("net: usb: qmi_wwan: add qmap mux protocol support")
Cc: Daniele Palmas <dnlplm@gmail.com>
Signed-off-by: Reinhard Speyerer <rspmn@arcor.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 3 deletions

diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c
index d9a6699abe59..fd3d078a1923 100644
--- a/drivers/net/usb/qmi_wwan.c
+++ b/drivers/net/usb/qmi_wwan.c
@@ -153,7 +153,7 @@ static bool qmimux_has_slaves(struct usbnet *dev)
 
 static int qmimux_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 {
-        unsigned int len, offset = 0;
+        unsigned int len, offset = 0, pad_len, pkt_len;
         struct qmimux_hdr *hdr;
         struct net_device *net;
         struct sk_buff *skbn;
@@ -171,10 +171,16 @@ static int qmimux_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
                 if (hdr->pad & 0x80)
                         goto skip;
 
+                /* extract padding length and check for valid length info */
+                pad_len = hdr->pad & 0x3f;
+                if (len == 0 || pad_len >= len)
+                        goto skip;
+                pkt_len = len - pad_len;
+
                 net = qmimux_find_dev(dev, hdr->mux_id);
                 if (!net)
                         goto skip;
-                skbn = netdev_alloc_skb(net, len);
+                skbn = netdev_alloc_skb(net, pkt_len);
                 if (!skbn)
                         return 0;
                 skbn->dev = net;
@@ -191,7 +197,7 @@ static int qmimux_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
                         goto skip;
                 }
 
-                skb_put_data(skbn, skb->data + offset + qmimux_hdr_sz, len);
+                skb_put_data(skbn, skb->data + offset + qmimux_hdr_sz, pkt_len);
                 if (netif_rx(skbn) != NET_RX_SUCCESS)
                         return 0;