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SubjectRe: [PATCH] Fix an inproper alignment accessing in irda protocol stack
From
From: "Luke Yang" <luke.adi@gmail.com>
Date: Wed, 14 Jun 2006 10:29:19 +0800

> --- net/irda/irlmp.c.old 2006-06-08 14:49:20.000000000 +0800
> +++ net/irda/irlmp.c 2006-06-14 10:00:22.000000000 +0800
> @@ -849,7 +849,10 @@
> }
>
> /* Construct new discovery info to be used by IrLAP, */
> - u16ho(irlmp->discovery_cmd.data.hints) = irlmp->hints.word;
> + irlmp->discovery_cmd.data.hints[0] = \
> + le16_to_cpu(irlmp->hints.word) & 0xff;
> + irlmp->discovery_cmd.data.hints[1] = \
> + (le16_to_cpu(irlmp->hints.word) & 0xff00) >> 8;
>
> /*
> * Set character set for device name (we use ASCII), and

I decided in the end to fix this differently.

We have a portable unaligned access interface, via get_unaligned() and
put_unaligned() in asm/unaligned.h, which makes sure there is no
penalty for platforms whose cpu does unaligned memory accesses
transparently.

diff --git a/net/irda/irlmp.c b/net/irda/irlmp.c
index c19e9ce..57ea160 100644
--- a/net/irda/irlmp.c
+++ b/net/irda/irlmp.c
@@ -44,6 +44,8 @@
#include <net/irda/irlmp.h>
#include <net/irda/irlmp_frame.h>

+#include <asm/unaligned.h>
+
static __u8 irlmp_find_free_slsap(void);
static int irlmp_slsap_inuse(__u8 slsap_sel);

@@ -840,6 +842,7 @@ void irlmp_do_expiry(void)
void irlmp_do_discovery(int nslots)
{
struct lap_cb *lap;
+ __u16 *data_hintsp;

/* Make sure the value is sane */
if ((nslots != 1) && (nslots != 6) && (nslots != 8) && (nslots != 16)){
@@ -849,7 +852,8 @@ void irlmp_do_discovery(int nslots)
}

/* Construct new discovery info to be used by IrLAP, */
- u16ho(irlmp->discovery_cmd.data.hints) = irlmp->hints.word;
+ data_hintsp = (__u16 *) irlmp->discovery_cmd.data.hints;
+ put_unaligned(irlmp->hints.word, data_hintsp);

/*
* Set character set for device name (we use ASCII), and
-
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