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    SubjectRe: [050/107] block: check for proper length of iov entries earlier in blk_rq_map_user_iov()
    On Fri, Nov 04, 2011 at 07:06:16PM +0000, Ben Hutchings wrote:
    > On Fri, Nov 04, 2011 at 10:14:26AM -0700, Greg KH wrote:
    > > On Fri, Nov 04, 2011 at 03:24:16PM +0000, Ben Hutchings wrote:
    > > > 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'.
    > >
    > > Then the fix should go upstream first :)
    >
    > But if I'm right, this is a non-fix and doesn't belong in the
    > longterm update.

    Doesn't this still fix one issue here, just not both of them described,
    right?

    thanks,

    greg k-h


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