From: Kees Cook <keescook@chromium.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org,
alex.popov@linux.com, catalin.marinas@arm.com,
linux-kernel@vger.kernel.org, luto@kernel.org, will@kernel.org
Subject: Re: [PATCH v2 09/13] lkdtm/stackleak: rework boundary management
Date: Wed, 4 May 2022 12:07:57 -0700 [thread overview]
Message-ID: <202205041205.803FD491@keescook> (raw)
In-Reply-To: <20220427173128.2603085-10-mark.rutland@arm.com>
On Wed, Apr 27, 2022 at 06:31:24PM +0100, Mark Rutland wrote:
> There are a few problems with the way the LKDTM STACKLEAK_ERASING test
> manipulates the stack pointer and boundary values:
>
> * It uses the address of a local variable to determine the current stack
> pointer, rather than using current_stack_pointer directly. As the
> local variable could be placed anywhere within the stack frame, this
> can be an over-estimate of the true stack pointer value.
>
> * Is uses an estiamte of the current stack pointer as the upper boundary
> when scanning for poison, even though prior functions could have used
> more stack (and may have updated current->lowest stack accordingly).
>
> * A pr_info() call is made in the middle of the test. As the printk()
> code is out-of-line and will make use of the stack, this could clobber
> poison and/or adjust current->lowest_stack. It would be better to log
> the metadata after the body of the test to avoid such problems.
Yeah, I noticed this too when I was testing the v1 series. I started
cleaning it up, but your version is much better. :)
--
Kees Cook
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WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org,
alex.popov@linux.com, catalin.marinas@arm.com,
linux-kernel@vger.kernel.org, luto@kernel.org, will@kernel.org
Subject: Re: [PATCH v2 09/13] lkdtm/stackleak: rework boundary management
Date: Wed, 4 May 2022 12:07:57 -0700 [thread overview]
Message-ID: <202205041205.803FD491@keescook> (raw)
In-Reply-To: <20220427173128.2603085-10-mark.rutland@arm.com>
On Wed, Apr 27, 2022 at 06:31:24PM +0100, Mark Rutland wrote:
> There are a few problems with the way the LKDTM STACKLEAK_ERASING test
> manipulates the stack pointer and boundary values:
>
> * It uses the address of a local variable to determine the current stack
> pointer, rather than using current_stack_pointer directly. As the
> local variable could be placed anywhere within the stack frame, this
> can be an over-estimate of the true stack pointer value.
>
> * Is uses an estiamte of the current stack pointer as the upper boundary
> when scanning for poison, even though prior functions could have used
> more stack (and may have updated current->lowest stack accordingly).
>
> * A pr_info() call is made in the middle of the test. As the printk()
> code is out-of-line and will make use of the stack, this could clobber
> poison and/or adjust current->lowest_stack. It would be better to log
> the metadata after the body of the test to avoid such problems.
Yeah, I noticed this too when I was testing the v1 series. I started
cleaning it up, but your version is much better. :)
--
Kees Cook
next prev parent reply other threads:[~2022-05-04 19:09 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-27 17:31 [PATCH v2 00/13] stackleak: fixes and rework Mark Rutland
2022-04-27 17:31 ` Mark Rutland
2022-04-27 17:31 ` [PATCH v2 01/13] arm64: stackleak: fix current_top_of_stack() Mark Rutland
2022-04-27 17:31 ` Mark Rutland
2022-05-04 16:41 ` Catalin Marinas
2022-05-04 16:41 ` Catalin Marinas
2022-05-04 19:01 ` Kees Cook
2022-05-04 19:01 ` Kees Cook
2022-05-04 19:55 ` Catalin Marinas
2022-05-04 19:55 ` Catalin Marinas
2022-05-05 8:25 ` Will Deacon
2022-05-05 8:25 ` Will Deacon
2022-05-08 17:24 ` Alexander Popov
2022-05-08 17:24 ` Alexander Popov
2022-05-10 11:36 ` Mark Rutland
2022-05-10 11:36 ` Mark Rutland
2022-04-27 17:31 ` [PATCH v2 02/13] stackleak: move skip_erasing() check earlier Mark Rutland
2022-04-27 17:31 ` Mark Rutland
2022-05-08 17:44 ` Alexander Popov
2022-05-08 17:44 ` Alexander Popov
2022-05-10 11:40 ` Mark Rutland
2022-05-10 11:40 ` Mark Rutland
2022-04-27 17:31 ` [PATCH v2 03/13] stackleak: remove redundant check Mark Rutland
2022-04-27 17:31 ` Mark Rutland
2022-05-08 18:17 ` Alexander Popov
2022-05-08 18:17 ` Alexander Popov
2022-05-10 11:46 ` Mark Rutland
2022-05-10 11:46 ` Mark Rutland
2022-05-11 3:00 ` Kees Cook
2022-05-11 3:00 ` Kees Cook
2022-05-11 8:02 ` Mark Rutland
2022-05-11 8:02 ` Mark Rutland
2022-05-11 14:44 ` Kees Cook
2022-05-11 14:44 ` Kees Cook
2022-05-12 9:14 ` Mark Rutland
2022-05-12 9:14 ` Mark Rutland
2022-05-15 16:17 ` Alexander Popov
2022-05-15 16:17 ` Alexander Popov
2022-05-24 10:03 ` Mark Rutland
2022-05-24 10:03 ` Mark Rutland
2022-05-26 22:09 ` Alexander Popov
2022-05-26 22:09 ` Alexander Popov
2022-04-27 17:31 ` [PATCH v2 04/13] stackleak: rework stack low bound handling Mark Rutland
2022-04-27 17:31 ` Mark Rutland
2022-04-27 17:31 ` [PATCH v2 05/13] stackleak: clarify variable names Mark Rutland
2022-04-27 17:31 ` Mark Rutland
2022-05-08 20:49 ` Alexander Popov
2022-05-08 20:49 ` Alexander Popov
2022-05-10 13:01 ` Mark Rutland
2022-05-10 13:01 ` Mark Rutland
2022-05-11 3:05 ` Kees Cook
2022-05-11 3:05 ` Kees Cook
2022-04-27 17:31 ` [PATCH v2 06/13] stackleak: rework stack high bound handling Mark Rutland
2022-04-27 17:31 ` Mark Rutland
2022-05-08 21:27 ` Alexander Popov
2022-05-08 21:27 ` Alexander Popov
2022-05-10 11:22 ` Mark Rutland
2022-05-10 11:22 ` Mark Rutland
2022-05-15 16:32 ` Alexander Popov
2022-05-15 16:32 ` Alexander Popov
2022-04-27 17:31 ` [PATCH v2 07/13] stackleak: rework poison scanning Mark Rutland
2022-04-27 17:31 ` Mark Rutland
2022-05-09 13:51 ` Alexander Popov
2022-05-09 13:51 ` Alexander Popov
2022-05-10 13:13 ` Mark Rutland
2022-05-10 13:13 ` Mark Rutland
2022-05-15 17:33 ` Alexander Popov
2022-05-15 17:33 ` Alexander Popov
2022-05-24 13:31 ` Mark Rutland
2022-05-24 13:31 ` Mark Rutland
2022-05-26 23:25 ` Alexander Popov
2022-05-26 23:25 ` Alexander Popov
2022-05-31 18:13 ` Kees Cook
2022-05-31 18:13 ` Kees Cook
2022-06-03 16:55 ` Alexander Popov
2022-06-03 16:55 ` Alexander Popov
2022-04-27 17:31 ` [PATCH v2 08/13] lkdtm/stackleak: avoid spurious failure Mark Rutland
2022-04-27 17:31 ` Mark Rutland
2022-04-27 17:31 ` [PATCH v2 09/13] lkdtm/stackleak: rework boundary management Mark Rutland
2022-04-27 17:31 ` Mark Rutland
2022-05-04 19:07 ` Kees Cook [this message]
2022-05-04 19:07 ` Kees Cook
2022-04-27 17:31 ` [PATCH v2 10/13] lkdtm/stackleak: prevent unexpected stack usage Mark Rutland
2022-04-27 17:31 ` Mark Rutland
2022-04-27 17:31 ` [PATCH v2 11/13] lkdtm/stackleak: check stack boundaries Mark Rutland
2022-04-27 17:31 ` Mark Rutland
2022-04-27 17:31 ` [PATCH v2 12/13] stackleak: add on/off stack variants Mark Rutland
2022-04-27 17:31 ` Mark Rutland
2022-04-27 17:31 ` [PATCH v2 13/13] arm64: entry: use stackleak_erase_on_task_stack() Mark Rutland
2022-04-27 17:31 ` Mark Rutland
2022-05-04 16:42 ` Catalin Marinas
2022-05-04 16:42 ` Catalin Marinas
2022-05-04 19:16 ` [PATCH v2 00/13] stackleak: fixes and rework Kees Cook
2022-05-04 19:16 ` Kees Cook
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