Messages in this thread | | | Date | Thu, 8 Jun 2006 00:30:15 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] Fix an inproper alignment accessing in irda protocol stack |
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On Thu, 8 Jun 2006 15:15:11 +0800 "Luke Yang" <luke.adi@gmail.com> wrote:
> 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. > > Signed-off-by: Luke Yang <luke.adi@gmail.com> > > irlmp.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletion(-) > > --- net/irda/irlmp.c.old 2006-06-08 14:49:20.000000000 +0800 > +++ net/irda/irlmp.c 2006-06-08 14:54:29.000000000 +0800 > @@ -849,7 +849,8 @@ > } > > /* Construct new discovery info to be used by IrLAP, */ > - u16ho(irlmp->discovery_cmd.data.hints) = irlmp->hints.word; > + irlmp->discovery_cmd.data.hints[0] = irlmp->hints.word & 0xff; > + irlmp->discovery_cmd.data.hints[1] = (irlmp->hints.word & 0xff00) >> 8;
This change will have the effect of swapping those two bytes on big-endian machines.
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