Re: [PATCH 2/3] scsi: megaraid_sas: check user-provided offsets

Arnd Bergmann
2021-01-04T22:25:58Z

On Mon, Jan 4, 2021 at 6:48 PM Phil Oester <kernel@linuxace.com> wrote:
>
> On Sun, Jan 03, 2021 at 05:26:29PM +0100, Arnd Bergmann wrote:
> > Thank you for the report and bisecting the issue, and sorry this broke
> > your system!
> >
> > Fortunately, the patch is fairly small, so there are only a limited number
> > of things that could go wrong. I haven't tried to analyze that message,
> > but I have two ideas:
> >
> > a) The added ioc->sense_off check gets triggered and the code relies
> > on the data being written outside of the structure
> >
> > b) the address actually needs to always be written as a 64-bit value
> > regardless of the instance->consistent_mask_64bit flag, as the
> > driver did before. This looked like it was done in error.
> >
> > Can you try the patch below instead of the revert and see if that
> > resolves the regression, and if it triggers the warning message I
> > add?
>
> Thanks Arnd, I tried your patch and it resolves the regression. It does not
> trigger the warning message you added.

Ok, thanks for testing! That would mean the range check is correct,
but the sense pointer must indeed be treated as a 64-bit entity
regardless of instance->consistent_mask_64bit, or at least the
upper 32 bit must be zero when the flag is unset, rather than
the recycled previous value.

I'll send a proper fix shortly, it would be nice if you could give it
another spin, but the behavior should be the same as this patch.

Arnd