diff mbox

drivers/net/usb/asix.c Fix unaligned access

Message ID AANLkTiliFhlbe7HAOyn9O3935MkmEuRumLKYY7Ew4DXQ@mail.gmail.com
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Neil Jones May 10, 2010, 4:06 p.m. UTC 
From b277dbc256de7b1a8c47ca374914c097ff4cdd50 Mon Sep 17 00:00:00 2001
From: Neil Jones <NeilJay@gmail.com>
Date: Thu, 6 May 2010 11:20:53 +0100
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>
---
 drivers/net/usb/asix.c |   37 ++++++++++++++++++++++++++++++++++++-
 1 files changed, 36 insertions(+), 1 deletions(-)

               } else {
--
1.5.5.2

Comments

David Miller May 18, 2010, 12:18 a.m. UTC | #1 
From: Neil Jones <neiljay@gmail.com>
Date: Mon, 10 May 2010 17:06:01 +0100

> 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>

Applied, thanks.
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diff mbox

Patch

diff --git a/drivers/net/usb/asix.c b/drivers/net/usb/asix.c
index a516185..5b4f0df 100644
--- a/drivers/net/usb/asix.c
+++ b/drivers/net/usb/asix.c
@@ -319,16 +319,51 @@  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) {
                       deverr(dev,"asix_rx_fixup() Bad RX Length %d", size);
                       return 0;
               }
               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);