linux-kernel - Re: [PATCH] x86/ioremap: tighten integer overflow checking

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Message-ID: <20181025070816.3e77nr25mskrkzqg@mwanda>
Date:   Thu, 25 Oct 2018 10:08:16 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Juergen Gross <jgross@...e.com>
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] x86/ioremap: tighten integer overflow checking



On Thu, Oct 25, 2018 at 08:28:44AM +0200, Juergen Gross wrote:
> On 25/10/2018 08:16, Dan Carpenter wrote:
> > The current check is a bit off in the case where "phys_addr + size"
> > wraps to zero because then "last_addr" is set to ULONG_MAX which is >=
> > phys_addr.
> 
> And -2 would be okay?
> 

If you see any patches from me it's static checker stuff...

I guess the original is actually fine because the -1 re-wraps back to
what we wanted it to be.  We also do verify that size is correct in
__ioremap_check_mem() so I can't see a problem here after all.

regards,
dan carpenter