From 9c412942a0bb19ba18f7bd939d42eff1e132a901 Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Tue, 3 May 2011 07:49:25 +0000 Subject: [PATCH] ipheth: Properly distinguish length and alignment in URBs and skbs The USB protocol this driver implements appears to require 2 bytes of padding in front of each received packet. This used to be equal to the value of NET_IP_ALIGN on x86, so the driver abused that constant and mostly worked, but this is no longer the case. The driver also mixed up the URB and packet lengths, resulting in 2 bytes of junk at the end of the skb. Introduce a private constant for the 2 bytes of padding; fix this confusion and check for the under-length case. Signed-off-by: Ben Hutchings Signed-off-by: David S. Miller --- drivers/net/usb/ipheth.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/drivers/net/usb/ipheth.c b/drivers/net/usb/ipheth.c index 7d42f9a2c068..81126ff85e05 100644 --- a/drivers/net/usb/ipheth.c +++ b/drivers/net/usb/ipheth.c @@ -65,6 +65,7 @@ #define IPHETH_USBINTF_PROTO 1 #define IPHETH_BUF_SIZE 1516 +#define IPHETH_IP_ALIGN 2 /* padding at front of URB */ #define IPHETH_TX_TIMEOUT (5 * HZ) #define IPHETH_INTFNUM 2 @@ -202,18 +203,21 @@ static void ipheth_rcvbulk_callback(struct urb *urb) return; } - len = urb->actual_length; - buf = urb->transfer_buffer; + if (urb->actual_length <= IPHETH_IP_ALIGN) { + dev->net->stats.rx_length_errors++; + return; + } + len = urb->actual_length - IPHETH_IP_ALIGN; + buf = urb->transfer_buffer + IPHETH_IP_ALIGN; - skb = dev_alloc_skb(NET_IP_ALIGN + len); + skb = dev_alloc_skb(len); if (!skb) { err("%s: dev_alloc_skb: -ENOMEM", __func__); dev->net->stats.rx_dropped++; return; } - skb_reserve(skb, NET_IP_ALIGN); - memcpy(skb_put(skb, len), buf + NET_IP_ALIGN, len - NET_IP_ALIGN); + memcpy(skb_put(skb, len), buf, len); skb->dev = dev->net; skb->protocol = eth_type_trans(skb, dev->net); -- 2.20.1