Re: [PATCH] Fix an inproper alignment accessing in irda protocol stack

[Luke Yang]

Hi all,

For "struct irda_device_info" in irda.h:
struct irda_device_info {
      __u32       saddr;    /* Address of local interface */
      __u32       daddr;    /* Address of remote device */
      char        info[22]; /* Description */
      __u8        charset;  /* Charset used for description */
      __u8        hints[2]; /* Hint bits */
};
 The "hints" member aligns at the third byte of a word, an odd
address. So if we visit "hints" as a short in irlmp.c:

  u16ho(irlmp->discovery_cmd.data.hints) = irlmp->hints.word;

will cause alignment problem on some machines. Architectures with
strict alignment rules do not allow 16-bit read on an odd address. I
use le16_to_cpu to do the converting.

Signed-off-by: Luke Yang <luke.adi@xxxxxxxxx>

irlmp.c |    5 ++++-
1 files changed, 4 insertions(+), 1 deletion(-)

--- 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

--
Best regards,
Luke Yang
luke.adi@xxxxxxxxx
--- 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