linux-kernel - Re: [PATCH] x86/sgx: Fix deadloop in __sgx_alloc_epc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-Id: <D3XKBPX6DBX4.2BYXD4D5NZGWZ@kernel.org>
Date: Wed, 04 Sep 2024 17:17:24 +0300
From: "Jarkko Sakkinen" <jarkko@...nel.org>
To: "Aaron Lu" <aaron.lu@...el.com>
Cc: "Dave Hansen" <dave.hansen@...ux.intel.com>, <x86@...nel.org>,
 <linux-sgx@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "Zhimin Luo"
 <zhimin.luo@...el.com>
Subject: Re: [PATCH] x86/sgx: Fix deadloop in __sgx_alloc_epc_page()

On Wed Sep 4, 2024 at 4:39 AM EEST, Aaron Lu wrote:
> On Tue, Sep 03, 2024 at 07:05:40PM +0300, Jarkko Sakkinen wrote:
> > On Fri Aug 30, 2024 at 9:14 AM EEST, Aaron Lu wrote:
> > > On Thu, Aug 29, 2024 at 07:44:13PM +0300, Jarkko Sakkinen wrote:
> > > > On Thu Aug 29, 2024 at 5:38 AM EEST, Aaron Lu wrote:
> > > > > When current node doesn't have a EPC section configured by firmware and
> > > > > all other EPC sections memory are used up, CPU can stuck inside the
> > > > > while loop in __sgx_alloc_epc_page() forever and soft lockup will happen.
> > > > > Note how nid_of_current will never equal to nid in that while loop because
> > > >                                                      ~~~~
> > > > 
> > > > Oh *that* while loop ;-) Please be more specific.
> > >
> > > What about:
> > > Note how nid_of_current will never be equal to nid in the while loop that
> > > searches an available EPC page from remote nodes because nid_of_current is
> > > not set in sgx_numa_mask.
> > 
> > That would work I think!
>
> While rewriting the changelog, I find it more natural to explain this
> "while loop" when I first mentioned it, i.e.
>
>     When the current node doesn't have an EPC section configured by firmware
>     and all other EPC sections are used up, CPU can get stuck inside the
>     while loop that looks for an available EPC page from remote nodes
>     indefinitely, leading to a soft lockup. Note how nid_of_current will
>     never be equal to nid in that while loop because nid_of_current is not
>     set in sgx_numa_mask.
>
> I hope this looks fine to you.

Yes, it is. I just want the storyline to the commit message as
a reminder why we did this, that's all. It helps a lot later on
when having to look into commit history.

BR, Jarkko