linux-kernel - Re: [PATCH] arm64: Correctly bounds check virt_addr

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20160921200601.GA24734@remoulade>
Date:   Wed, 21 Sep 2016 21:06:01 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Laura Abbott <labbott@...hat.com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Kees Cook <keescook@...omium.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: Correctly bounds check virt_addr_valid

On Wed, Sep 21, 2016 at 12:34:46PM -0700, Laura Abbott wrote:
> On 09/21/2016 10:58 AM, Mark Rutland wrote:
> >Are there other potentially-broken users of virt_addr_valid? It's not
> >clear to me what some drivers are doing with this, and therefore whether
> >we need to cc stable.
> 
> The number of users is pretty limited. Some of them use it as a debugging
> check, others are using it more like hardened usercopy. The number of
> users that would actually affect arm64 seems so small I don't think it's
> worth trying to backport to stable.

Ok.

> Hardened usercopy was getting hit particularly hard because usercopy was
> happening on all types of memory whereas the drivers tend to be more limited
> in scope.

Sure.

> >Given the common sub-expression, perhaps it would be better to leave
> >these as-is, but prefix them with '_', and after the #endif, have
> >something like:
> >
> >#define _virt_addr_is_linear(kaddr)	(((u64)(kaddr)) >= PAGE_OFFSET)
> >#define virt_addr_valid(kaddr)		(_virt_addr_is_linear(kaddr) && _virt_addr_valid(kaddr))
> >
> 
> Good suggestion.

FWIW, with that, feel free to add:

Acked-by: Mark Rutland <mark.rutland@....com>

Thanks,
Mark.