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From: Michael Ellerman <mpe@ellerman.id.au>
To: linux-kernel@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>,
	Balbir Singh <bsingharora@gmail.com>,
	Daniel Micay <danielmicay@gmail.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Rik van Riel <riel@redhat.com>,
	Casey Schaufler <casey@schaufler-ca.com>,
	PaX Team <pageexec@freemail.hu>,
	Brad Spengler <spender@grsecurity.net>,
	Russell King <linux@armlinux.org.uk>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Tony Luck <tony.luck@intel.com>,
	Fenghua Yu <fenghua.yu@intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	x86@kernel.org, Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@suse.de>,
	Mathias
Subject: Re: [PATCH v3 02/11] mm: Hardened usercopy
Date: Thu, 21 Jul 2016 16:52:09 +1000	[thread overview]
Message-ID: <57907120.4137420a.5bfa2.2bacSMTPIN_ADDED_BROKEN@mx.google.com> (raw)
In-Reply-To: <1468619065-3222-3-git-send-email-keescook@chromium.org>

Kees Cook <keescook@chromium.org> writes:

> diff --git a/mm/usercopy.c b/mm/usercopy.c
> new file mode 100644
> index 000000000000..e4bf4e7ccdf6
> --- /dev/null
> +++ b/mm/usercopy.c
> @@ -0,0 +1,234 @@
...
> +
> +/*
> + * Checks if a given pointer and length is contained by the current
> + * stack frame (if possible).
> + *
> + *	0: not at all on the stack
> + *	1: fully within a valid stack frame
> + *	2: fully on the stack (when can't do frame-checking)
> + *	-1: error condition (invalid stack position or bad stack frame)
> + */
> +static noinline int check_stack_object(const void *obj, unsigned long len)
> +{
> +	const void * const stack = task_stack_page(current);
> +	const void * const stackend = stack + THREAD_SIZE;

That allows access to the entire stack, including the struct thread_info,
is that what we want - it seems dangerous? Or did I miss a check
somewhere else?

We have end_of_stack() which computes the end of the stack taking
thread_info into account (end being the opposite of your end above).

cheers

--
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WARNING: multiple messages have this Message-ID (diff)
From: Michael Ellerman <mpe@ellerman.id.au>
To: Kees Cook <keescook@chromium.org>, linux-kernel@vger.kernel.org
Cc: Balbir Singh <bsingharora@gmail.com>,
	Daniel Micay <danielmicay@gmail.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Rik van Riel <riel@redhat.com>,
	Casey Schaufler <casey@schaufler-ca.com>,
	PaX Team <pageexec@freemail.hu>,
	Brad Spengler <spender@grsecurity.net>,
	Russell King <linux@armlinux.org.uk>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Tony Luck <tony.luck@intel.com>,
	Fenghua Yu <fenghua.yu@intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	x86@kernel.org, Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@suse.de>,
	Mathias Krause <minipli@googlemail.com>, Jan Kara <jack@suse.cz>,
	Vitaly Wool <vitalywool@gmail.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Laura Abbott <labbott@fedoraproject.org>,
	linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org,
	linux-arch@vger.kernel.org, linux-mm@kvack.org,
	kernel-hardening@lists.openwall.com
Subject: Re: [PATCH v3 02/11] mm: Hardened usercopy
Date: Thu, 21 Jul 2016 16:52:09 +1000	[thread overview]
Message-ID: <57907120.4137420a.5bfa2.2bacSMTPIN_ADDED_BROKEN@mx.google.com> (raw)
In-Reply-To: <1468619065-3222-3-git-send-email-keescook@chromium.org>

Kees Cook <keescook@chromium.org> writes:

> diff --git a/mm/usercopy.c b/mm/usercopy.c
> new file mode 100644
> index 000000000000..e4bf4e7ccdf6
> --- /dev/null
> +++ b/mm/usercopy.c
> @@ -0,0 +1,234 @@
...
> +
> +/*
> + * Checks if a given pointer and length is contained by the current
> + * stack frame (if possible).
> + *
> + *	0: not at all on the stack
> + *	1: fully within a valid stack frame
> + *	2: fully on the stack (when can't do frame-checking)
> + *	-1: error condition (invalid stack position or bad stack frame)
> + */
> +static noinline int check_stack_object(const void *obj, unsigned long len)
> +{
> +	const void * const stack = task_stack_page(current);
> +	const void * const stackend = stack + THREAD_SIZE;

That allows access to the entire stack, including the struct thread_info,
is that what we want - it seems dangerous? Or did I miss a check
somewhere else?

We have end_of_stack() which computes the end of the stack taking
thread_info into account (end being the opposite of your end above).

cheers

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

  parent reply	other threads:[~2016-07-21  6:52 UTC|newest]

Thread overview: 257+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-15 21:44 [PATCH v3 00/11] mm: Hardened usercopy Kees Cook
2016-07-15 21:44 ` [kernel-hardening] " Kees Cook
2016-07-15 21:44 ` Kees Cook
2016-07-15 21:44 ` Kees Cook
2016-07-15 21:44 ` Kees Cook
2016-07-15 21:44 ` Kees Cook
2016-07-15 21:44 ` [PATCH v3 01/11] mm: Implement stack frame object validation Kees Cook
2016-07-15 21:44   ` [kernel-hardening] " Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44 ` [PATCH v3 02/11] mm: Hardened usercopy Kees Cook
2016-07-15 21:44   ` [kernel-hardening] " Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-19  1:06   ` Laura Abbott
2016-07-19  1:06     ` [kernel-hardening] " Laura Abbott
2016-07-19  1:06     ` Laura Abbott
2016-07-19  1:06     ` Laura Abbott
2016-07-19  1:06     ` Laura Abbott
2016-07-19  1:06     ` Laura Abbott
2016-07-19 18:48     ` Kees Cook
2016-07-19 18:48       ` [kernel-hardening] " Kees Cook
2016-07-19 18:48       ` Kees Cook
2016-07-19 18:48       ` Kees Cook
2016-07-19 18:48       ` Kees Cook
2016-07-19 18:48       ` Kees Cook
2016-07-19 18:48       ` Kees Cook
2016-07-19 22:00       ` [PATCH] mm: Add is_migrate_cma_page Laura Abbott
2016-07-19 22:00         ` [kernel-hardening] " Laura Abbott
2016-07-19 22:00         ` Laura Abbott
2016-07-19 22:00         ` Laura Abbott
2016-07-19 22:00         ` Laura Abbott
2016-07-19 22:00         ` Laura Abbott
2016-07-19 22:40         ` Kees Cook
2016-07-19 22:40           ` [kernel-hardening] " Kees Cook
2016-07-19 22:40           ` Kees Cook
2016-07-19 22:40           ` Kees Cook
2016-07-19 22:40           ` Kees Cook
2016-07-19 22:40           ` Kees Cook
2016-07-19 22:40           ` Kees Cook
2016-07-20 10:24       ` [PATCH v3 02/11] mm: Hardened usercopy Balbir Singh
2016-07-20 10:24         ` [kernel-hardening] " Balbir Singh
2016-07-20 10:24         ` Balbir Singh
2016-07-20 10:24         ` Balbir Singh
2016-07-20 10:24         ` Balbir Singh
2016-07-20 10:24         ` Balbir Singh
2016-07-20 10:24         ` Balbir Singh
2016-07-20 10:24         ` Balbir Singh
2016-07-20 15:36         ` Laura Abbott
2016-07-20 15:36           ` [kernel-hardening] " Laura Abbott
2016-07-20 15:36           ` Laura Abbott
2016-07-20 15:36           ` Laura Abbott
2016-07-20 15:36           ` Laura Abbott
2016-07-20 15:36           ` Laura Abbott
2016-07-20 15:36           ` Laura Abbott
2016-07-19  1:52   ` Laura Abbott
2016-07-19  1:52     ` [kernel-hardening] " Laura Abbott
2016-07-19  1:52     ` Laura Abbott
2016-07-19  1:52     ` Laura Abbott
2016-07-19  1:52     ` Laura Abbott
2016-07-19  1:52     ` Laura Abbott
2016-07-19 19:12     ` Kees Cook
2016-07-19 19:12       ` [kernel-hardening] " Kees Cook
2016-07-19 19:12       ` Kees Cook
2016-07-19 19:12       ` Kees Cook
2016-07-19 19:12       ` Kees Cook
2016-07-19 19:12       ` Kees Cook
2016-07-19 19:12       ` Kees Cook
2016-07-19 22:55       ` Kees Cook
2016-07-19 22:55         ` [kernel-hardening] " Kees Cook
2016-07-19 22:55         ` Kees Cook
2016-07-19 22:55         ` Kees Cook
2016-07-19 22:55         ` Kees Cook
2016-07-19 22:55         ` Kees Cook
2016-07-19 22:55         ` Kees Cook
2016-07-19  9:21   ` Christian Borntraeger
2016-07-19  9:21     ` [kernel-hardening] " Christian Borntraeger
2016-07-19  9:21     ` Christian Borntraeger
2016-07-19  9:21     ` Christian Borntraeger
2016-07-19  9:21     ` Christian Borntraeger
2016-07-19  9:21     ` Christian Borntraeger
2016-07-19 19:31     ` Kees Cook
2016-07-19 19:31       ` [kernel-hardening] " Kees Cook
2016-07-19 19:31       ` Kees Cook
2016-07-19 19:31       ` Kees Cook
2016-07-19 19:31       ` Kees Cook
2016-07-19 19:31       ` Kees Cook
2016-07-19 19:31       ` Kees Cook
2016-07-19 20:14       ` Christian Borntraeger
2016-07-19 20:14         ` [kernel-hardening] " Christian Borntraeger
2016-07-19 20:14         ` Christian Borntraeger
2016-07-19 20:14         ` Christian Borntraeger
2016-07-19 20:14         ` Christian Borntraeger
2016-07-19 20:14         ` Christian Borntraeger
2016-07-19 20:14         ` Christian Borntraeger
2016-07-19 20:34         ` Kees Cook
2016-07-19 20:34           ` [kernel-hardening] " Kees Cook
2016-07-19 20:34           ` Kees Cook
2016-07-19 20:34           ` Kees Cook
2016-07-19 20:34           ` Kees Cook
2016-07-19 20:34           ` Kees Cook
2016-07-19 20:34           ` Kees Cook
2016-07-19 20:44           ` Christian Borntraeger
2016-07-19 20:44             ` [kernel-hardening] " Christian Borntraeger
2016-07-19 20:44             ` Christian Borntraeger
2016-07-19 20:44             ` Christian Borntraeger
2016-07-19 20:44             ` Christian Borntraeger
2016-07-19 20:44             ` Christian Borntraeger
2016-07-19 20:44             ` Christian Borntraeger
2016-07-21  6:52   ` Michael Ellerman
2016-07-21  6:52   ` Michael Ellerman
2016-07-21  6:52   ` Michael Ellerman
2016-07-21  6:52     ` [kernel-hardening] " Michael Ellerman
2016-07-21  6:52     ` Michael Ellerman
2016-07-21  6:52   ` Michael Ellerman
2016-07-21  6:52   ` Michael Ellerman [this message]
2016-07-21  6:52     ` Michael Ellerman
2016-07-21  6:52   ` Michael Ellerman
     [not found]   ` <5790711f.2350420a.b4287.2cc0SMTPIN_ADDED_BROKEN@mx.google.com>
2016-07-21 18:34     ` Kees Cook
2016-07-21 18:34       ` [kernel-hardening] " Kees Cook
2016-07-21 18:34       ` Kees Cook
2016-07-21 18:34       ` Kees Cook
2016-07-21 18:34       ` Kees Cook
2016-07-21 18:34       ` Kees Cook
2016-07-21 18:34       ` Kees Cook
2016-07-22 17:45       ` Josh Poimboeuf
2016-07-22 17:45         ` [kernel-hardening] " Josh Poimboeuf
2016-07-22 17:45         ` Josh Poimboeuf
2016-07-22 17:45         ` Josh Poimboeuf
2016-07-22 17:45         ` Josh Poimboeuf
2016-07-22 17:45         ` Josh Poimboeuf
2016-07-22 17:45         ` Josh Poimboeuf
2016-07-25  9:27         ` David Laight
2016-07-25  9:27           ` [kernel-hardening] " David Laight
2016-07-25  9:27           ` David Laight
2016-07-25  9:27           ` David Laight
2016-07-25  9:27           ` David Laight
2016-07-25  9:27           ` David Laight
2016-07-25  9:27           ` David Laight
2016-07-26  2:09           ` Michael Ellerman
2016-07-26  2:09             ` [kernel-hardening] " Michael Ellerman
2016-07-26  2:09             ` Michael Ellerman
2016-07-26  2:09             ` Michael Ellerman
2016-07-26  2:09             ` Michael Ellerman
2016-07-26  2:09             ` Michael Ellerman
2016-07-26  2:09             ` Michael Ellerman
2016-07-26  2:09             ` Michael Ellerman
2016-07-26  2:03         ` Michael Ellerman
2016-07-26  2:03           ` [kernel-hardening] " Michael Ellerman
2016-07-26  2:03           ` Michael Ellerman
2016-07-26  2:03           ` Michael Ellerman
2016-07-26  4:46           ` Kees Cook
2016-07-26  4:46             ` [kernel-hardening] " Kees Cook
2016-07-26  4:46             ` Kees Cook
2016-07-26  4:46             ` Kees Cook
2016-07-26  4:46             ` Kees Cook
2016-07-26  4:46             ` Kees Cook
2016-07-26  4:46             ` Kees Cook
2016-07-15 21:44 ` [PATCH v3 03/11] x86/uaccess: Enable hardened usercopy Kees Cook
2016-07-15 21:44   ` [kernel-hardening] " Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44 ` [PATCH v3 04/11] ARM: uaccess: " Kees Cook
2016-07-15 21:44   ` [kernel-hardening] " Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44 ` [PATCH v3 05/11] arm64/uaccess: " Kees Cook
2016-07-15 21:44   ` [kernel-hardening] " Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44 ` [PATCH v3 06/11] ia64/uaccess: " Kees Cook
2016-07-15 21:44   ` [kernel-hardening] " Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44 ` [PATCH v3 07/11] powerpc/uaccess: " Kees Cook
2016-07-15 21:44   ` [kernel-hardening] " Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44 ` [PATCH v3 08/11] sparc/uaccess: " Kees Cook
2016-07-15 21:44   ` [kernel-hardening] " Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44 ` [PATCH v3 09/11] s390/uaccess: " Kees Cook
2016-07-15 21:44   ` [kernel-hardening] " Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44 ` [PATCH v3 10/11] mm: SLAB hardened usercopy support Kees Cook
2016-07-15 21:44   ` [kernel-hardening] " Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44 ` [PATCH v3 11/11] mm: SLUB " Kees Cook
2016-07-15 21:44   ` [kernel-hardening] " Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-15 21:44   ` Kees Cook
2016-07-18  8:26 ` [PATCH v3 00/11] mm: Hardened usercopy Balbir Singh
2016-07-18  8:26   ` [kernel-hardening] " Balbir Singh
2016-07-18  8:26   ` Balbir Singh
2016-07-18  8:26   ` Balbir Singh
2016-07-18  8:26   ` Balbir Singh
2016-07-18  8:26   ` Balbir Singh
2016-07-18  8:26   ` Balbir Singh
2016-07-20  9:52 ` David Laight
2016-07-20  9:52   ` [kernel-hardening] " David Laight
2016-07-20  9:52   ` David Laight
2016-07-20  9:52   ` David Laight
2016-07-20  9:52   ` David Laight
2016-07-20  9:52   ` David Laight
2016-07-20  9:52   ` David Laight
2016-07-20 15:31   ` Kees Cook
2016-07-20 15:31     ` [kernel-hardening] " Kees Cook
2016-07-20 15:31     ` Kees Cook
2016-07-20 15:31     ` Kees Cook
2016-07-20 15:31     ` Kees Cook
2016-07-20 15:31     ` Kees Cook
2016-07-20 15:31     ` Kees Cook
2016-07-20 16:02     ` David Laight
2016-07-20 16:02       ` [kernel-hardening] " David Laight
2016-07-20 16:02       ` David Laight
2016-07-20 16:02       ` David Laight
2016-07-20 16:02       ` David Laight
2016-07-20 16:02       ` David Laight
2016-07-20 16:02       ` David Laight
2016-07-20 16:22       ` Rik van Riel
2016-07-20 16:22         ` [kernel-hardening] " Rik van Riel
2016-07-20 16:22         ` Rik van Riel
2016-07-20 16:22         ` Rik van Riel
2016-07-20 16:22         ` Rik van Riel
2016-07-20 16:22         ` Rik van Riel
2016-07-20 17:44       ` Kees Cook
2016-07-20 17:44         ` [kernel-hardening] " Kees Cook
2016-07-20 17:44         ` Kees Cook
2016-07-20 17:44         ` Kees Cook
2016-07-20 17:44         ` Kees Cook
2016-07-20 17:44         ` Kees Cook
2016-07-20 17:44         ` Kees Cook

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