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authorNeil Jones <NeilJay@gmail.com>2010-05-17 17:18:28 -0700
committerDavid S. Miller <davem@davemloft.net>2010-05-17 17:18:28 -0700
commit3f78d1f210ff89af77f042ab7f4a8fee39feb1c9 (patch)
treef29742a1a73c27a88c7ac701a7a06ac1c2f7973a /drivers/net/usb
parente7a3af5d8cd782b84e6ca4e4dcc8613be1a809f0 (diff)
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>
Diffstat (limited to 'drivers/net/usb')
-rw-r--r--drivers/net/usb/asix.c34
1 files changed, 33 insertions, 1 deletions
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);