linux-kernel - Re: DMA error when sg->offset value is greater than PAGE

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:   Wed, 27 Sep 2017 21:29:23 +0000
From:   Casey Leedom <leedom@...lsio.com>
To:     "Raj, Ashok" <ashok.raj@...el.com>,
        Robin Murphy <robin.murphy@....com>
CC:     Dan Williams <dan.j.williams@...el.com>,
        "Harsh Jain" <Harsh@...lsio.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "dwmw2@...radead.org" <dwmw2@...radead.org>,
        Michael Werner <werner@...lsio.com>, "nd@....com" <nd@....com>
Subject: Re: DMA error when sg->offset value is greater than PAGE_SIZE in
 Intel IOMMU

Hey Raj,

  Let us know if you need help in gathering more debugging information.  For
the time being we've decided to ERRATA the use of the Intel I/O MMU with
IPsec till we Root Cause the issue.  But this is still at the top of Harsh's
bug list.
 
  With Robin's comments, I'm almost sure that the:

    (iov_pfn + sg->offset) << VTD_PAGE_SHIFT)

in your suggested patch is an issue.  iov_pfn is a Page Frame Number and
sg->offset is a Byte Offset.  It feels like this should be:

    size_t page_off = sg->offset & ~VTD_PAGE_MASK;
    unsigned long pfn_off = sg->offset >> VTD_PAGE_MASK;
    ...
    sg->dma_address = ((dma_addr_t)
                       (iov_pfn + pfn_off) << VTD_PAGE_SHIFT) + page_off;

When Harsh tried your original patch, Harsh' test system wouldn't even boot.

Casey