On Mon, Apr 14, 2014 at 08:45:16AM -0700, James Bottomley wrote:
> Your subject line is very tame. It should be the one line summary of
> why we apply the patch, so it should read something like
>
> hpsa: fix NULL deref in performant mode
>
> On Thu, 2014-04-10 at 17:17 -0500, scameron@xxxxxxxxxxxxxxxxxx wrote:
> > Without this, you'll see a null pointer dereference in
> > hpsa_enter_performant_mode().
>
> The description should be more comprehensible.
>
> I'm clear that the use before initialisation is a bug ... I'm less clear
> on why it causes an oops.
>
> > Signed-off-by: Stephen M. Cameron <scameron@xxxxxxxxxxxxxxxxxx>
> > ---
> > drivers/scsi/hpsa.c | 4 ++++
> > 1 files changed, 4 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
> > index 8cf4a0c..ef4dfdd 100644
> > --- a/drivers/scsi/hpsa.c
> > +++ b/drivers/scsi/hpsa.c
> > @@ -7463,6 +7463,10 @@ static void hpsa_put_ctlr_into_performant_mode(struct ctlr_info *h)
> > if (hpsa_simple_mode)
> > return;
> >
> > + trans_support = readl(&(h->cfgtable->TransportSupport));
> > + if (!(trans_support & PERFORMANT_MODE))
> > + return;
> > +
> > /* Check for I/O accelerator mode support */
> > if (trans_support & CFGTBL_Trans_io_accel1) {
> > transMethod |= CFGTBL_Trans_io_accel1 |
>
> Shouldn't you be moving this check from its previous location, rather
> than adding a new one that makes the original obsolete?
Oh... I didn't notice that. So that's what happened to that hunk.
Yes, that is what should be done.
I will resend the patch after fixing up this and the commit message.
-- steve
>
> James
>
> ---
>
> diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
> index 8cf4a0c..9a6e4a2 100644
> --- a/drivers/scsi/hpsa.c
> +++ b/drivers/scsi/hpsa.c
> @@ -7463,6 +7463,10 @@ static void hpsa_put_ctlr_into_performant_mode(struct ctlr_info *h)
> if (hpsa_simple_mode)
> return;
>
> + trans_support = readl(&(h->cfgtable->TransportSupport));
> + if (!(trans_support & PERFORMANT_MODE))
> + return;
> +
> /* Check for I/O accelerator mode support */
> if (trans_support & CFGTBL_Trans_io_accel1) {
> transMethod |= CFGTBL_Trans_io_accel1 |
> @@ -7479,10 +7483,6 @@ static void hpsa_put_ctlr_into_performant_mode(struct ctlr_info *h)
> }
>
> /* TODO, check that this next line h->nreply_queues is correct */
> - trans_support = readl(&(h->cfgtable->TransportSupport));
> - if (!(trans_support & PERFORMANT_MODE))
> - return;
> -
> h->nreply_queues = h->msix_vector > 0 ? h->msix_vector : 1;
> hpsa_get_max_perf_mode_cmds(h);
> /* Performant mode ring buffer and supporting data structures */
>
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