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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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