From 3f78d1f210ff89af77f042ab7f4a8fee39feb1c9 Mon Sep 17 00:00:00 2001
From: Neil Jones <NeilJay@gmail.com>
Date: Mon, 17 May 2010 17:18:28 -0700
Subject: [PATCH] drivers/net/usb/asix.c: Fix unaligned accesses
Using this driver can cause unaligned accesses in the IP layer
This has been fixed by aligning the skb data correctly using the
spare room left over by the 4 byte header inserted between packets
by the device.
Signed-off-by: Neil Jones <NeilJay@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
drivers/net/usb/asix.c | 34 +++++++++++++++++++++++++++++++++-
1 file changed, 33 insertions(+), 1 deletion(-)
diff --git a/drivers/net/usb/asix.c b/drivers/net/usb/asix.c
index 8e7d2374558b..66c5e89326c1 100644
--- a/drivers/net/usb/asix.c
+++ b/drivers/net/usb/asix.c
@@ -322,8 +322,29 @@ static int asix_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
/* get the packet length */
size = (u16) (header & 0x0000ffff);
- if ((skb->len) - ((size + 1) & 0xfffe) == 0)
+ if ((skb->len) - ((size + 1) & 0xfffe) == 0) {
+ u8 alignment = (u32)skb->data & 0x3;
+ if (alignment != 0x2) {
+ /*
+ * not 16bit aligned so use the room provided by
+ * the 32 bit header to align the data
+ *
+ * note we want 16bit alignment as MAC header is
+ * 14bytes thus ip header will be aligned on
+ * 32bit boundary so accessing ipheader elements
+ * using a cast to struct ip header wont cause
+ * an unaligned accesses.
+ */
+ u8 realignment = (alignment + 2) & 0x3;
+ memmove(skb->data - realignment,
+ skb->data,
+ size);
+ skb->data -= realignment;
+ skb_set_tail_pointer(skb, size);
+ }
return 2;
+ }
+
if (size > ETH_FRAME_LEN) {
netdev_err(dev->net, "asix_rx_fixup() Bad RX Length %d\n",
size);
@@ -331,7 +352,18 @@ static int asix_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
}
ax_skb = skb_clone(skb, GFP_ATOMIC);
if (ax_skb) {
+ u8 alignment = (u32)packet & 0x3;
ax_skb->len = size;
+
+ if (alignment != 0x2) {
+ /*
+ * not 16bit aligned use the room provided by
+ * the 32 bit header to align the data
+ */
+ u8 realignment = (alignment + 2) & 0x3;
+ memmove(packet - realignment, packet, size);
+ packet -= realignment;
+ }
ax_skb->data = packet;
skb_set_tail_pointer(ax_skb, size);
usbnet_skb_return(dev, ax_skb);
--
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