All of lore.kernel.org
 help / color / mirror / Atom feed
From: Luis Henriques <lhenriques@suse.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	Kernel Hardening <kernel-hardening@lists.openwall.com>,
	Greg KH <gregkh@linuxfoundation.org>, X86 ML <x86@kernel.org>,
	Ingo Molnar <mingo@redhat.com>, Andy Lutomirski <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Alan Cox <alan@linux.intel.com>
Subject: Re: [PATCH v4 07/10] x86: narrow out of bounds syscalls to sys_read under speculation
Date: Tue, 6 Feb 2018 22:51:32 +0000	[thread overview]
Message-ID: <20180206225132.yewppdrnut35gzrh@hermes.olymp> (raw)
In-Reply-To: <CAPcyv4ihN6fy5-vBtfA0PuwXvCAj8-rMhtQmevh5sdYxbH3Yfw@mail.gmail.com>

On Tue, Feb 06, 2018 at 11:48:45AM -0800, Dan Williams wrote:
> On Tue, Feb 6, 2018 at 11:29 AM, Luis Henriques <lhenriques@suse.com> wrote:
> > On Thu, Jan 18, 2018 at 04:02:21PM -0800, Dan Williams wrote:
> >> The syscall table base is a user controlled function pointer in kernel
> >> space. Like, 'get_user, use 'MASK_NOSPEC' to prevent any out of bounds
> >> speculation. While retpoline prevents speculating into the user
> >> controlled target it does not stop the pointer de-reference, the concern
> >> is leaking memory relative to the syscall table base.
> >
> > This patch seems to cause a regression.  An easy way to reproduce what
> > I'm seeing is to run the samples/statx/test-statx.  Here's what I see
> > when I have this patchset applied:
> >
> > # ./test-statx /tmp
> > statx(/tmp) = -1
> > /tmp: Bad file descriptor
> >
> > Reverting this single patch seems to fix it.
> 
> Just to clarify, when you say "this patch" you mean:
> 
>      2fbd7af5af86 x86/syscall: Sanitize syscall table de-references
> under speculation
> 
> ...not this early MASK_NOSPEC version of the patch, right?

*sigh*

Looks like I spent some good amount of time hunting a non-issue just
because I have enough old branches hanging around to confusing me :-(

Sorry for the noise.

Cheers,
--
Luís

WARNING: multiple messages have this Message-ID (diff)
From: Luis Henriques <lhenriques@suse.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	Kernel Hardening <kernel-hardening@lists.openwall.com>,
	Greg KH <gregkh@linuxfoundation.org>, X86 ML <x86@kernel.org>,
	Ingo Molnar <mingo@redhat.com>, Andy Lutomirski <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Alan Cox <alan@linux.intel.com>
Subject: Re: [PATCH v4 07/10] x86: narrow out of bounds syscalls to sys_read under speculation
Date: Tue, 6 Feb 2018 22:51:32 +0000	[thread overview]
Message-ID: <20180206225132.yewppdrnut35gzrh@hermes.olymp> (raw)
In-Reply-To: <CAPcyv4ihN6fy5-vBtfA0PuwXvCAj8-rMhtQmevh5sdYxbH3Yfw@mail.gmail.com>

On Tue, Feb 06, 2018 at 11:48:45AM -0800, Dan Williams wrote:
> On Tue, Feb 6, 2018 at 11:29 AM, Luis Henriques <lhenriques@suse.com> wrote:
> > On Thu, Jan 18, 2018 at 04:02:21PM -0800, Dan Williams wrote:
> >> The syscall table base is a user controlled function pointer in kernel
> >> space. Like, 'get_user, use 'MASK_NOSPEC' to prevent any out of bounds
> >> speculation. While retpoline prevents speculating into the user
> >> controlled target it does not stop the pointer de-reference, the concern
> >> is leaking memory relative to the syscall table base.
> >
> > This patch seems to cause a regression.  An easy way to reproduce what
> > I'm seeing is to run the samples/statx/test-statx.  Here's what I see
> > when I have this patchset applied:
> >
> > # ./test-statx /tmp
> > statx(/tmp) = -1
> > /tmp: Bad file descriptor
> >
> > Reverting this single patch seems to fix it.
> 
> Just to clarify, when you say "this patch" you mean:
> 
>      2fbd7af5af86 x86/syscall: Sanitize syscall table de-references
> under speculation
> 
> ...not this early MASK_NOSPEC version of the patch, right?

*sigh*

Looks like I spent some good amount of time hunting a non-issue just
because I have enough old branches hanging around to confusing me :-(

Sorry for the noise.

Cheers,

  parent reply	other threads:[~2018-02-06 22:51 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-19  0:01 [PATCH v4 00/10] prevent bounds-check bypass via speculative execution Dan Williams
2018-01-19  0:01 ` [kernel-hardening] " Dan Williams
2018-01-19  0:01 ` Dan Williams
2018-01-19  0:01 ` [PATCH v4 01/10] Documentation: document array_ptr Dan Williams
2018-01-19  0:01   ` [kernel-hardening] " Dan Williams
2018-01-19  0:01 ` [PATCH v4 02/10] asm/nospec, array_ptr: sanitize speculative array de-references Dan Williams
2018-01-19  0:01   ` [kernel-hardening] " Dan Williams
2018-01-19 10:20   ` Jann Horn
2018-01-19 17:48     ` Adam Sampson
2018-01-19 17:48       ` Adam Sampson
2018-01-19 17:48       ` Adam Sampson
2018-01-19 17:48       ` Adam Sampson
2018-01-19 18:12       ` Dan Williams
2018-01-19 18:18         ` Will Deacon
2018-01-19 18:18           ` Will Deacon
2018-01-19 18:26           ` [kernel-hardening] " Dan Williams
2018-01-19 18:18     ` Linus Torvalds
2018-01-19 18:18       ` Linus Torvalds
2018-01-19 20:55       ` [kernel-hardening] " Dan Williams
2018-01-25  7:09   ` Cyril Novikov
2018-01-25  7:09     ` [kernel-hardening] " Cyril Novikov
2018-01-25 22:37     ` Dan Williams
2018-01-25 22:37       ` [kernel-hardening] " Dan Williams
2018-01-19  0:01 ` [PATCH v4 03/10] x86: implement array_ptr_mask() Dan Williams
2018-01-19  0:01   ` [kernel-hardening] " Dan Williams
2018-01-19  0:01 ` [PATCH v4 04/10] x86: introduce __uaccess_begin_nospec and ifence Dan Williams
2018-01-19  0:01   ` [kernel-hardening] " Dan Williams
2018-01-19  0:02 ` [PATCH v4 05/10] x86, __get_user: use __uaccess_begin_nospec Dan Williams
2018-01-19  0:02   ` [kernel-hardening] " Dan Williams
2018-01-19  0:02 ` [PATCH v4 06/10] x86, get_user: use pointer masking to limit speculation Dan Williams
2018-01-19  0:02   ` [kernel-hardening] " Dan Williams
2018-01-19  0:02 ` [PATCH v4 07/10] x86: narrow out of bounds syscalls to sys_read under speculation Dan Williams
2018-01-19  0:02   ` [kernel-hardening] " Dan Williams
2018-01-24 14:40   ` Jiri Slaby
2018-01-24 14:40     ` [kernel-hardening] " Jiri Slaby
2018-02-06 19:29   ` Luis Henriques
2018-02-06 19:48     ` Dan Williams
2018-02-06 20:26       ` Linus Torvalds
2018-02-06 20:37         ` Dan Williams
2018-02-06 20:42           ` Linus Torvalds
2018-02-06 20:43             ` Linus Torvalds
2018-02-06 20:49             ` Andy Lutomirski
2018-02-06 20:58               ` Linus Torvalds
2018-02-06 21:37                 ` Dan Williams
2018-02-06 22:52                   ` Linus Torvalds
2018-02-07  0:33                     ` Dan Williams
2018-02-07  1:23                       ` Linus Torvalds
2018-02-06 22:51       ` Luis Henriques [this message]
2018-02-06 22:51         ` Luis Henriques
2018-01-19  0:02 ` [PATCH v4 08/10] vfs, fdtable: prevent bounds-check bypass via speculative execution Dan Williams
2018-01-19  0:02   ` [kernel-hardening] " Dan Williams
2018-01-19  0:02 ` [PATCH v4 09/10] kvm, x86: fix spectre-v1 mitigation Dan Williams
2018-01-19  0:02   ` [kernel-hardening] " Dan Williams
2018-01-19  8:42   ` Paolo Bonzini
2018-01-19  8:42     ` [kernel-hardening] " Paolo Bonzini
2018-01-19  0:02 ` [PATCH v4 10/10] nl80211: sanitize array index in parse_txq_params Dan Williams
2018-01-19  0:02   ` [kernel-hardening] " Dan Williams
2018-01-19  0:02   ` Dan Williams
2018-01-21 10:37   ` Johannes Berg
2018-01-21 10:37     ` [kernel-hardening] " Johannes Berg
2018-01-21 10:37     ` Johannes Berg
2018-01-20  6:58 ` [PATCH v4 00/10] prevent bounds-check bypass via speculative execution Dan Williams
2018-01-20  6:58   ` [kernel-hardening] " Dan Williams
2018-01-20  6:58   ` Dan Williams
2018-01-20 16:56   ` Alexei Starovoitov
2018-01-20 16:56     ` [kernel-hardening] " Alexei Starovoitov
2018-01-20 16:56     ` Alexei Starovoitov
2018-01-20 17:07     ` Alexei Starovoitov
2018-01-20 17:07       ` [kernel-hardening] " Alexei Starovoitov
2018-01-20 17:07       ` Alexei Starovoitov

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=20180206225132.yewppdrnut35gzrh@hermes.olymp \
    --to=lhenriques@suse.com \
    --cc=akpm@linux-foundation.org \
    --cc=alan@linux.intel.com \
    --cc=dan.j.williams@intel.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=hpa@zytor.com \
    --cc=kernel-hardening@lists.openwall.com \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=mingo@redhat.com \
    --cc=tglx@linutronix.de \
    --cc=torvalds@linux-foundation.org \
    --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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.