From: Borislav Petkov <bp@alien8.de>
To: Jarkko Sakkinen <jarkko@kernel.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
linux-sgx@vger.kernel.org,
Sean Christopherson <seanjc@google.com>,
Haitao Huang <haitao.huang@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Jethro Beekman <jethro@fortanix.com>
Subject: Re: [PATCH v3] x86/sgx: Synchronize encl->srcu in sgx_encl_release().
Date: Tue, 5 Jan 2021 15:57:49 +0100 [thread overview]
Message-ID: <20210105145749.GF28649@zn.tnic> (raw)
In-Reply-To: <20201216134920.21161-1-jarkko@kernel.org>
On Wed, Dec 16, 2020 at 03:49:20PM +0200, Jarkko Sakkinen wrote:
> Add synchronize_srcu_expedited() to sgx_encl_release() to catch a grace
> period initiated by sgx_mmu_notifier_release().
>
> A trivial example of a failing sequence with tasks A and B:
>
> 1. A: -> sgx_release()
> 2. B: -> sgx_mmu_notifier_release()
> 3. B: -> list_del_rcu()
> 3. A: -> sgx_encl_release()
> 4. A: -> cleanup_srcu_struct()
>
> The loop in sgx_release() observes an empty list because B has removed its
> entry in the middle, and calls cleanup_srcu_struct() before B has a chance
> to calls synchronize_srcu().
Leading to what? NULL ptr?
https://lkml.kernel.org/r/X9e2jOWz1hfXVpQ5@google.com
already suggested that you should explain the bug better and add the
splat but I'm still missing that explanation.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-01-05 14:58 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-16 13:49 Jarkko Sakkinen
2021-01-04 20:22 ` Haitao Huang
2021-01-11 23:41 ` Jarkko Sakkinen
2021-01-05 14:57 ` Borislav Petkov [this message]
2021-01-12 0:08 ` Jarkko Sakkinen
2021-01-12 18:35 ` Borislav Petkov
2021-01-12 20:11 ` Paul E. McKenney
2021-01-13 17:18 ` Jarkko Sakkinen
2021-01-13 17:46 ` Paul E. McKenney
2021-01-13 18:00 ` Borislav Petkov
2021-01-13 18:22 ` Paul E. McKenney
2021-01-15 1:49 ` Jarkko Sakkinen
2021-01-14 4:42 ` Haitao Huang
2021-01-15 9:58 ` Jarkko Sakkinen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210105145749.GF28649@zn.tnic \
--to=bp@alien8.de \
--cc=haitao.huang@linux.intel.com \
--cc=hpa@zytor.com \
--cc=jarkko@kernel.org \
--cc=jethro@fortanix.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-sgx@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=seanjc@google.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®