Re: [PATCH 7/10] cciss: use safer test on the result of find_first_zero_bit
From: Julia Lawall
Date: Wed Jun 04 2014 - 11:10:36 EST
On Wed, 4 Jun 2014, scameron@xxxxxxxxxxxxxxxxxx wrote:
> > Find_first_zero_bit considers BITS_PER_LONG bits at a time, and thus may
> > return a larger number than the maximum position argument if that position
> > is not a multiple of BITS_PER_LONG.
> >
> > The semantic match that finds this problem is as follows:
> > (http://coccinelle.lip6.fr/)
> >
> > // <smpl>
> > @@
> > expression e1,e2,e3;
> > statement S1,S2;
> > @@
> >
> > e1 = find_first_zero_bit(e2,e3)
> > ...
> > if (e1
> > - ==
> > + >=
> > e3)
> > S1 else S2
> > // </smpl>
> >
> > Signed-off-by: Julia Lawall <Julia.Lawall@xxxxxxx>
> >
> > ---
> > drivers/block/cciss.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff -u -p a/drivers/block/cciss.c b/drivers/block/cciss.c
> > --- a/drivers/block/cciss.c
> > +++ b/drivers/block/cciss.c
> > @@ -980,7 +980,7 @@ static CommandList_struct *cmd_alloc(ctl
> >
> > do {
> > i = find_first_zero_bit(h->cmd_pool_bits, h->nr_cmds);
> > - if (i == h->nr_cmds)
> > + if (i >= h->nr_cmds)
> > return NULL;
> > } while (test_and_set_bit(i, h->cmd_pool_bits) != 0);
> > c = h->cmd_pool + i;
>
>
> Thanks. Ack.
>
> You can add
>
> Reviewed-by: Stephen M. Cameron <scameron@xxxxxxxxxxxxxxxxxx>
>
> to this patch if you want.
>
> You might consider adding "Cc: stable@xxxxxxxxxxxxxxx" into the
> sign-off area as well.
Likewise here, the change is not needed.
julia
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