Re: [PATCH v3 17/28] x86/sgx: fix a NULL pointer

Jarkko Sakkinen
2023-07-17T14:34:29Z

On Mon Jul 17, 2023 at 1:14 PM UTC, Haitao Huang wrote:
> On Mon, 17 Jul 2023 07:49:27 -0500, Jarkko Sakkinen <jarkko@kernel.org>
> wrote:
>
> > On Mon Jul 17, 2023 at 12:48 PM UTC, Jarkko Sakkinen wrote:
> >> On Wed Jul 12, 2023 at 11:01 PM UTC, Haitao Huang wrote:
> >> > Under heavy load, the SGX EPC reclaimers (ksgxd or future EPC cgroup
> >> > worker) may reclaim SECS EPC page for an enclave and set
> >> > encl->secs.epc_page to NULL. But the SECS EPC page is required for
> >> EAUG
> >> > in #PF handler and is used without checking for NULL and reloading.
> >> >
> >> > Fix this by checking if SECS is loaded before EAUG and load it if it
> >> was
> >> > reclaimed.
> >> >
> >> > Signed-off-by: Haitao Huang <haitao.huang@linux.intel.com>
> >>
> >> A bug fix should be 1/*.
> >
> > And a fixes tag.
> >
> > Or is there a bug that is momentized by the earlier patches? This patch
> > feels confusing to say the least.
> >
>
> It happens in heavy reclaiming cases, just extremely rare when EPC
> accounting is not partitioned into cgroups. Will add fix tag with the
> related EDMM patch. And move this as the first patch.

I understand, it is just a good practice to follow, i.e. have prelude
and then the "real" changes :-)

BR, Jarkko