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    SubjectRe: [050/107] block: check for proper length of iov entries earlier in blk_rq_map_user_iov()
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    On Wed, 2011-11-02 at 15:14 -0700, Greg KH wrote:
    > 2.6.32-longterm review patch. If anyone has any objections, please let us know.
    >
    > ------------------
    >
    > From: Xiaotian Feng <dfeng@redhat.com>
    >
    > commit 5478755616ae2ef1ce144dded589b62b2a50d575 upstream.
    >
    > commit 9284bcf checks for proper length of iov entries in
    > blk_rq_map_user_iov(). But if the map is unaligned, kernel
    > will break out the loop without checking for the proper length.
    > So we need to check the proper length before the unalign check.

    This will catch an unaligned zero-length entry. But there's still no
    check for zero-length iov entries *after* the unaligned entry.

    [...]
    > --- a/block/blk-map.c
    > +++ b/block/blk-map.c
    > @@ -201,12 +201,13 @@ int blk_rq_map_user_iov(struct request_q
    > for (i = 0; i < iov_count; i++) {
    > unsigned long uaddr = (unsigned long)iov[i].iov_base;
    >
    > + if (!iov[i].iov_len)
    > + return -EINVAL;
    > +
    > if (uaddr & queue_dma_alignment(q)) {
    > unaligned = 1;
    > break;

    I think the correct fix is just to remove the 'break'.

    Ben.

    > }
    > - if (!iov[i].iov_len)
    > - return -EINVAL;
    > }
    >
    > if (unaligned || (q->dma_pad_mask & len) || map_data)
    >

    --
    Ben Hutchings
    Sturgeon's Law: Ninety percent of everything is crap.
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