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    SubjectRe: [PATCH] NFS: Check lengths more thoroughly in NFS4 readdir XDR decode
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    On Thu, 2006-08-24 at 19:35 +0100, David Howells wrote:
    > So, what you've done is:
    >
    > -+ if (end - p < xlen)
    > ++ if (end - p < xlen + 1)
    > goto short_pkt;
    > + dprintk("filename = %*s\n", len, (char *)p);
    > + p += xlen;
    > len = ntohl(*p++); /* bitmap length */
    > - p += len;
    > - if (p + 1 > end)
    > -+ if (end - p < len)
    > ++ if (end - p < len + 1)
    > goto short_pkt;
    > + p += len;
    > attrlen = XDR_QUADLEN(ntohl(*p++));
    > - p += attrlen; /* attributes */
    > - if (p + 2 > end)
    > -+ if (end - p < attrlen + 1)
    > ++ if (end - p < attrlen + 2)
    >
    > But is this equivalent:
    >
    > -+ if (end - p < xlen)
    > ++ if (end - p <= xlen)
    > goto short_pkt;
    > + dprintk("filename = %*s\n", len, (char *)p);
    > + p += xlen;
    > len = ntohl(*p++); /* bitmap length */
    > - p += len;
    > - if (p + 1 > end)
    > -+ if (end - p < len)
    > ++ if (end - p <= len)
    > goto short_pkt;
    > + p += len;
    > attrlen = XDR_QUADLEN(ntohl(*p++));
    > - p += attrlen; /* attributes */
    > - if (p + 2 > end)
    > -+ if (end - p < attrlen + 1)
    > ++ if (end - p <= attrlen + 1)
    ^^^^^^^^^^^^^^
    >
    > Do you think?

    No. I find that mixture of < and <= is much less easy to read. Besides,
    the compiler should be able to optimise that for me.

    Cheers,
    Trond

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