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drivers/net/usb/asix.c: Fix unaligned accesses

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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>
This commit is contained in:
Neil Jones 2010-05-17 17:18:28 -07:00 committed by David S. Miller
parent e7a3af5d8c
commit 3f78d1f210
1 changed files with 33 additions and 1 deletions
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34
drivers/net/usb/asix.c
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@ -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);