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From: Mark Rutland <mark.rutland@arm.com>
To: Alexander Popov <alex.popov@linux.com>
Cc: Andy Lutomirski <luto@kernel.org>,
	Laura Abbott <labbott@redhat.com>,
	Kees Cook <keescook@chromium.org>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	kernel-hardening@lists.openwall.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] arm64: Clear the stack
Date: Mon, 14 May 2018 15:07:15 +0100	[thread overview]
Message-ID: <20180514140714.sfmvfpwco63eomor@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <c5bebf0b-9667-5725-2800-97c5a85635c4@linux.com>

On Mon, May 14, 2018 at 04:53:12PM +0300, Alexander Popov wrote:
> On 14.05.2018 13:06, Mark Rutland wrote:
> > I think it is reasonable to panic() here even with CONFIG_VMAP_STACK
> > selected.
> 
> It's too tough for CONFIG_VMAP_STACK on x86 - the system can proceed to live.
> Anyway, the check_alloca() code will not be shared between x86 and arm64, I've
> described the reasons in this thread. So I can have BUG() for CONFIG_VMAP_STACK
> on x86 and Laura can consistently use panic() on arm64.

If we need arch-specific implementations anyway, then that's fine by me.

> >> So we should not do it in check_alloca() as well, just use BUG() and
> >> hope for the best.
> > 
> > Regardless of whether we BUG() or panic(), we're hoping for the best.
> > 
> > Consistently using panic() here will keep things simpler, so any failure
> > reported will be easier to reason about, and easier to debug.
> 
> Let me keep BUG() for !CONFIG_SCHED_STACK_END_CHECK. I beware of using panic()
> by default, let distro/user decide this. I remember very well how I was shouted
> at, when this one was merged:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ce6fa91b93630396ca220c33dd38ffc62686d499

Sure; my comments needn't hold up your patches.

Thanks,
Mark.

WARNING: multiple messages have this Message-ID (diff)
From: mark.rutland@arm.com (Mark Rutland)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/2] arm64: Clear the stack
Date: Mon, 14 May 2018 15:07:15 +0100	[thread overview]
Message-ID: <20180514140714.sfmvfpwco63eomor@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <c5bebf0b-9667-5725-2800-97c5a85635c4@linux.com>

On Mon, May 14, 2018 at 04:53:12PM +0300, Alexander Popov wrote:
> On 14.05.2018 13:06, Mark Rutland wrote:
> > I think it is reasonable to panic() here even with CONFIG_VMAP_STACK
> > selected.
> 
> It's too tough for CONFIG_VMAP_STACK on x86 - the system can proceed to live.
> Anyway, the check_alloca() code will not be shared between x86 and arm64, I've
> described the reasons in this thread. So I can have BUG() for CONFIG_VMAP_STACK
> on x86 and Laura can consistently use panic() on arm64.

If we need arch-specific implementations anyway, then that's fine by me.

> >> So we should not do it in check_alloca() as well, just use BUG() and
> >> hope for the best.
> > 
> > Regardless of whether we BUG() or panic(), we're hoping for the best.
> > 
> > Consistently using panic() here will keep things simpler, so any failure
> > reported will be easier to reason about, and easier to debug.
> 
> Let me keep BUG() for !CONFIG_SCHED_STACK_END_CHECK. I beware of using panic()
> by default, let distro/user decide this. I remember very well how I was shouted
> at, when this one was merged:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ce6fa91b93630396ca220c33dd38ffc62686d499

Sure; my comments needn't hold up your patches.

Thanks,
Mark.

  reply	other threads:[~2018-05-14 14:07 UTC|newest]

Thread overview: 86+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-06 14:22 [PATCH v11 0/6] Introduce the STACKLEAK feature and a test for it Alexander Popov
2018-04-06 14:22 ` [PATCH v11 1/6] gcc-plugins: Clean up the cgraph_create_edge* macros Alexander Popov
2018-04-06 14:22 ` [PATCH v11 2/6] x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls Alexander Popov
2018-04-16 18:29   ` Kees Cook
2018-04-18 18:33     ` Laura Abbott
2018-04-18 18:50     ` Dave Hansen
2018-04-24  1:03       ` Kees Cook
2018-04-24  4:23   ` Dave Hansen
2018-04-30 23:48     ` Kees Cook
2018-05-02  8:42       ` Thomas Gleixner
2018-05-02 12:38         ` Kees Cook
2018-05-02 12:39           ` Thomas Gleixner
2018-05-02 12:51             ` Kees Cook
2018-05-02 21:02               ` Kees Cook
2018-05-06 10:04                 ` Thomas Gleixner
2018-04-06 14:22 ` [PATCH v11 3/6] gcc-plugins: Add STACKLEAK plugin for tracking the kernel stack Alexander Popov
2018-04-06 14:22 ` [PATCH v11 4/6] lkdtm: Add a test for STACKLEAK Alexander Popov
2018-04-06 14:22 ` [PATCH v11 5/6] fs/proc: Show STACKLEAK metrics in the /proc file system Alexander Popov
2018-04-06 14:22 ` [PATCH v11 6/6] doc: self-protection: Add information about STACKLEAK feature Alexander Popov
2018-05-02 20:33 ` [PATCH 0/2] Stackleak for arm64 Laura Abbott
2018-05-02 20:33   ` Laura Abbott
2018-05-02 20:33   ` [PATCH 1/2] stackleak: Update " Laura Abbott
2018-05-02 20:33     ` Laura Abbott
2018-05-02 20:33   ` [PATCH 2/2] arm64: Clear the stack Laura Abbott
2018-05-02 20:33     ` Laura Abbott
2018-05-02 21:31     ` Kees Cook
2018-05-02 21:31       ` Kees Cook
2018-05-02 23:07       ` Laura Abbott
2018-05-02 23:07         ` Laura Abbott
2018-05-02 23:37         ` Kees Cook
2018-05-02 23:37           ` Kees Cook
2018-05-03 16:05         ` Alexander Popov
2018-05-03 16:05           ` Alexander Popov
2018-05-03 16:45           ` Kees Cook
2018-05-03 16:45             ` Kees Cook
2018-05-03  7:19     ` Mark Rutland
2018-05-03  7:19       ` Mark Rutland
2018-05-03 11:37       ` Ard Biesheuvel
2018-05-03 11:37         ` Ard Biesheuvel
2018-05-03 17:33       ` Alexander Popov
2018-05-03 17:33         ` Alexander Popov
2018-05-03 19:09         ` Laura Abbott
2018-05-03 19:09           ` Laura Abbott
2018-05-04  8:30           ` Alexander Popov
2018-05-04  8:30             ` Alexander Popov
2018-05-04 11:09         ` Mark Rutland
2018-05-04 11:09           ` Mark Rutland
2018-05-06  8:22           ` Alexander Popov
2018-05-06  8:22             ` Alexander Popov
2018-05-11 15:50             ` Alexander Popov
2018-05-11 15:50               ` Alexander Popov
2018-05-11 16:13               ` Mark Rutland
2018-05-11 16:13                 ` Mark Rutland
2018-05-13  8:40                 ` Alexander Popov
2018-05-13  8:40                   ` Alexander Popov
2018-05-14  5:15                   ` Mark Rutland
2018-05-14  5:15                     ` Mark Rutland
2018-05-14  9:35                     ` Alexander Popov
2018-05-14  9:35                       ` Alexander Popov
2018-05-14 10:06                       ` Mark Rutland
2018-05-14 10:06                         ` Mark Rutland
2018-05-14 13:53                         ` Alexander Popov
2018-05-14 13:53                           ` Alexander Popov
2018-05-14 14:07                           ` Mark Rutland [this message]
2018-05-14 14:07                             ` Mark Rutland
2018-05-03 19:00       ` Laura Abbott
2018-05-03 19:00         ` Laura Abbott
2018-05-04 11:16         ` Mark Rutland
2018-05-04 11:16           ` Mark Rutland
2018-05-14 18:55 ` [PATCH v11 0/6] Introduce the STACKLEAK feature and a test for it Laura Abbott
  -- strict thread matches above, loose matches on Subject: below --
2018-07-18 21:10 [PATCH 0/2] Stackleak for arm64 Laura Abbott
2018-07-18 21:10 ` [PATCH 2/2] arm64: Clear the stack Laura Abbott
2018-07-18 21:10   ` Laura Abbott
2018-07-19  2:20   ` Kees Cook
2018-07-19  2:20     ` Kees Cook
2018-07-19 10:41   ` Alexander Popov
2018-07-19 10:41     ` Alexander Popov
2018-07-19 11:41   ` Mark Rutland
2018-07-19 11:41     ` Mark Rutland
2018-02-21  1:13 [PATCH 0/2] Stackleak for arm64 Laura Abbott
2018-02-21  1:13 ` [PATCH 2/2] arm64: Clear the stack Laura Abbott
2018-02-21  1:13   ` Laura Abbott
2018-02-21 15:38   ` Mark Rutland
2018-02-21 15:38     ` Mark Rutland
2018-02-21 23:53     ` Laura Abbott
2018-02-21 23:53       ` Laura Abbott
2018-02-22  1:35       ` Laura Abbott
2018-02-22  1:35         ` Laura Abbott

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