linux-kernel - Re: Fwd: New Defects reported by Coverity Scan for Linux

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Message-ID: <5349C119.7050208@zytor.com>
Date:	Sat, 12 Apr 2014 15:41:29 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Ville Syrjälä <ville.syrjala@...ux.intel.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>
CC:	Ingo Molnar <mingo@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Fwd: New Defects reported by Coverity Scan for Linux

On 04/12/2014 02:41 PM, Ville Syrjälä wrote:
> On Sat, Apr 12, 2014 at 07:29:29AM -0600, Bjorn Helgaas wrote:
>> FYI, looks like these were added by a4dff76924fe ("x86/gpu: Add Intel
>> graphics stolen memory quirk for gen2 platforms").
> 
> Some of the affected gen2 platforms do support up to 2GB of RAM which
> means that if the sign extension were to happen they could hit this.
> However I believe all gen2 platforms are 32bit which AFAIK makes size_t 
> 32 bits. So looks like we can't hit this in practice..
> 
> But if someone were to change the return type to 64bits we'd
> be in real danger, so I guess it would be better to fix the bug
> anyway.
> 
> -#define KB(x)  ((x) * 1024)
> +#define KB(x)  ((x) * 1024U)
> should be sufficient to eliminate the problem. If someone wants me to
> put that into a real patch and send it out let me know.
> 

Please do, but make it UL (in the Linux kernel context, unsigned long is
always equivalent to size_t/pointer size.)

	-hpa


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