linux-kernel - Re: [PATCH 02/21] arm64/iommu: improve mmap bounds checking

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

Message-ID: <20190407065923.GA9086@lst.de>
Date:   Sun, 7 Apr 2019 08:59:23 +0200
From:   Christoph Hellwig <hch@....de>
To:     Robin Murphy <robin.murphy@....com>
Cc:     Christoph Hellwig <hch@....de>, Joerg Roedel <joro@...tes.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        iommu@...ts.linux-foundation.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 02/21] arm64/iommu: improve mmap bounds checking

On Fri, Apr 05, 2019 at 06:30:52PM +0100, Robin Murphy wrote:
> On 27/03/2019 08:04, Christoph Hellwig wrote:
>> The nr_pages checks should be done for all mmap requests, not just those
>> using remap_pfn_range.
>
> Hmm, the logic in iommu_dma_mmap() inherently returns an error for the "off 
> >= nr_pages" case already. It's also supposed to be robust against the 
> "vma_pages(vma) > nr_pages - off" condition, although by making the partial 
> mapping and treating it as a success, rather than doing nothing and 
> returning an error. What's the exact motivation here?

Have one error check at the front of the function that is identical
to the mmap checks in the other dma_map_ops instances so that:

 a) we get the same error behavior for partial requests everywhere
 b) we can lift these checks into common code in the next round.