On Thu, 29 Oct 2015, Tomohiro Kusumi wrote:
> > 2015-10-28 8:03 GMT+09:00 Mikulas Patocka:
> > On Wed, 28 Oct 2015, Tomohiro Kusumi wrote:
> >
> > > It's always (sctx->nr_regions == nr_regions) considering
> > > the assignment right before this conditional, and this
> > > function is only used by .ctr.
> >
> > The variable sctx->nr_regions has type unsigned long and the variable
> > nr_regions has type sector_t.
> >
> > Thus the variables may be different when overflow happens.
> >
> > It could be changed to "if (nr_regions >= ULONG_MAX)".
>
> Sorry about that.
> Changed the conditional to "if (nr_regions >= ULONG_MAX)",
> and brought the assignment of nr_regions after sector_div()
> and the sanity check which looks more sane.
>
> Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@xxxxxxxxx>
> Reviewed-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Acked-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
> ---
> drivers/md/dm-switch.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/md/dm-switch.c b/drivers/md/dm-switch.c
> index 50fca46..e1b6722 100644
> --- a/drivers/md/dm-switch.c
> +++ b/drivers/md/dm-switch.c
> @@ -99,11 +99,11 @@ static int alloc_region_table(struct dm_target *ti, unsigned nr_paths)
> if (sector_div(nr_regions, sctx->region_size))
> nr_regions++;
>
> - sctx->nr_regions = nr_regions;
> - if (sctx->nr_regions != nr_regions || sctx->nr_regions >= ULONG_MAX) {
> + if (nr_regions >= ULONG_MAX) {
> ti->error = "Region table too large";
> return -EINVAL;
> }
> + sctx->nr_regions = nr_regions;
>
> nr_slots = nr_regions;
> if (sector_div(nr_slots, sctx->region_entries_per_slot))
> --
> 1.7.1
>
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