From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: linux-sgx@vger.kernel.org
Subject: Re: [PATCH v2 2/5] x86/sgx: Reject concurrent ioctls on single enclave
Date: Fri, 30 Aug 2019 01:22:08 +0300 [thread overview]
Message-ID: <20190829222208.tqcwo7xg4t4wiuv7@linux.intel.com> (raw)
In-Reply-To: <20190829184332.GA27262@linux.intel.com>
On Thu, Aug 29, 2019 at 11:43:33AM -0700, Sean Christopherson wrote:
> On Thu, Aug 29, 2019 at 09:14:38PM +0300, Jarkko Sakkinen wrote:
> > On Thu, Aug 29, 2019 at 09:00:01AM -0700, Sean Christopherson wrote:
> > > > #PF handler should be good as it has this conditional:
> > > >
> > > > flags = atomic_read(&encl->flags);
> > > >
> > > > if ((flags & SGX_ENCL_DEAD) || !(flags & SGX_ENCL_INITIALIZED))
> > > > return ERR_PTR(-EFAULT);
> > > >
> > > > What about the reclaimer?
> > >
> > > Can you elaborate? I'm not sure what you're asking.
> >
> > I'm thinking of a race between list_add() in the ioctl and
> > list_move_tail() in the reclaimer.
>
> Ah crud, I forgot that the reclaimer can manipulate the list of VA pages,
> I was thinking they were invisible to the reclaimer.
>
> > A quick way to fix this would be move sgx_alloc_va_page() from
> > sgx_encl_grow() and return NULL if a new allocation is required.
>
> We don't even need to do that, moving the list_add() from sgx_encl_grow()
> to its caller would be sufficient. Same concept, but the allocation would
> be handled by sgx_encl_grow() instead of having to duplicate that code in
> sgx_encl_add_page() and sgx_encl_create().
Yeah, that was whole point that list_add() cannot be done without
encl->lock. Anything that works goes...
/Jarkko
next prev parent reply other threads:[~2019-08-29 22:22 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-27 19:27 [PATCH v2 0/5] x86/sgx: Fix lock ordering bug w/ EADD Sean Christopherson
2019-08-27 19:27 ` [PATCH v2 1/5] x86/sgx: Convert encl->flags from an unsigned int to an atomic Sean Christopherson
2019-08-29 13:09 ` Jarkko Sakkinen
2019-08-29 15:59 ` Sean Christopherson
2019-08-29 18:01 ` Jarkko Sakkinen
2019-08-30 0:02 ` Sean Christopherson
2019-08-27 19:27 ` [PATCH v2 2/5] x86/sgx: Reject concurrent ioctls on single enclave Sean Christopherson
2019-08-29 13:15 ` Jarkko Sakkinen
2019-08-29 16:00 ` Sean Christopherson
2019-08-29 18:14 ` Jarkko Sakkinen
2019-08-29 18:43 ` Sean Christopherson
2019-08-29 22:22 ` Jarkko Sakkinen [this message]
2019-08-27 19:27 ` [PATCH v2 3/5] x86/sgx: Take encl->lock inside of mm->mmap_sem for EADD Sean Christopherson
2019-08-27 19:27 ` [PATCH v2 4/5] x86/sgx: Reject all ioctls on dead enclaves Sean Christopherson
2019-08-27 19:27 ` [PATCH v2 5/5] x86/sgx: Destroy the enclave if EEXTEND fails Sean Christopherson
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