linux-kernel - Re: [patch] edac i5000: fix pointer math in i5000_get_mc

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Message-ID: <20120302190932.GI22598@mwanda>
Date:	Fri, 2 Mar 2012 22:09:32 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	walter harms <wharms@....de>
Cc:	Eric Wollesen <ericw@...p.net>,
	Doug Thompson <dougthompson@...ssion.com>,
	list-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [patch] edac i5000: fix pointer math in i5000_get_mc_regs()

On Fri, Mar 02, 2012 at 10:00:06AM +0100, walter harms wrote:
> > diff --git a/drivers/edac/i5000_edac.c b/drivers/edac/i5000_edac.c
> > index 4dc3ac2..fcdc4ab 100644
> > --- a/drivers/edac/i5000_edac.c
> > +++ b/drivers/edac/i5000_edac.c
> > @@ -1130,7 +1130,7 @@ static void i5000_get_mc_regs(struct mem_ctl_info *mci)
> >  	pci_read_config_dword(pvt->system_address, AMBASE,
> >  			(u32 *) & pvt->ambase);
> >  	pci_read_config_dword(pvt->system_address, AMBASE + sizeof(u32),
> > -			((u32 *) & pvt->ambase) + sizeof(u32));
> > +			(u32 *)((char *) &pvt->ambase + sizeof(u32)));
> >  
> >  	maxdimmperch = pvt->maxdimmperch;
> >  	maxch = pvt->maxch;
> 
> i think this is hard to understand. personally i would prefer a union or other
> more obvious solutions. my suggestion would be to get rid of this.
> 
> u32 bottom,top;
>  	pci_read_config_dword(pvt->system_address, AMBASE,
>   			&bottom);
> 	pci_read_config_dword(pvt->system_address, AMBASE+ sizeof(u32),
>   			&top);
> 	maxdimmperch=(u64)top<<32|bottom;
> 	
> you can find this pattern in other parts of the kernel also.
> 

Sure.  I want to do this again anyway because I see I've missed some
other parts which have the same bug.  I'll resend a patch later.

regards,
dan carpenter

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