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From: Kees Cook <keescook@chromium.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Elena Reshetova <elena.reshetova@intel.com>,
	x86@kernel.org, Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Potapenko <glider@google.com>,
	Alexander Popov <alex.popov@linux.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Jann Horn <jannh@google.com>, Vlastimil Babka <vbabka@suse.cz>,
	David Hildenbrand <david@redhat.com>,
	Mike Rapoport <rppt@linux.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Randy Dunlap <rdunlap@infradead.org>,
	kernel-hardening@lists.openwall.com,
	linux-hardening@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v8 3/6] stack: Optionally randomize kernel stack offset each syscall
Date: Wed, 31 Mar 2021 23:31:39 -0700	[thread overview]
Message-ID: <202103312329.394CCA13CF@keescook> (raw)
In-Reply-To: <87v9973q54.ffs@nanos.tec.linutronix.de>

On Thu, Apr 01, 2021 at 12:38:31AM +0200, Thomas Gleixner wrote:
> On Wed, Mar 31 2021 at 14:54, Kees Cook wrote:
> > On Wed, Mar 31, 2021 at 09:53:26AM +0200, Thomas Gleixner wrote:
> >> On Tue, Mar 30 2021 at 13:57, Kees Cook wrote:
> >> > +/*
> >> > + * Do not use this anywhere else in the kernel. This is used here because
> >> > + * it provides an arch-agnostic way to grow the stack with correct
> >> > + * alignment. Also, since this use is being explicitly masked to a max of
> >> > + * 10 bits, stack-clash style attacks are unlikely. For more details see
> >> > + * "VLAs" in Documentation/process/deprecated.rst
> >> > + * The asm statement is designed to convince the compiler to keep the
> >> > + * allocation around even after "ptr" goes out of scope.
> >> 
> >> Nit. That explanation of "ptr" might be better placed right at the
> >> add_random...() macro.
> >
> > Ah, yes! Fixed in v9.
> 
> Hmm, looking at V9 the "ptr" thing got lost ....

I put the comment inline in the macro directly above the asm().

> > Do you want to take this via -tip (and leave off the arm64 patch until
> > it is acked), or would you rather it go via arm64? (I've sent v9 now...)
> 
> Either way is fine.

Since the arm64 folks have been a bit busy, can you just put this in
-tip and leave off the arm64 patch for now?

Thanks!

-- 
Kees Cook

WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Elena Reshetova <elena.reshetova@intel.com>,
	x86@kernel.org, Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Potapenko <glider@google.com>,
	Alexander Popov <alex.popov@linux.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Jann Horn <jannh@google.com>, Vlastimil Babka <vbabka@suse.cz>,
	David Hildenbrand <david@redhat.com>,
	Mike Rapoport <rppt@linux.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Randy Dunlap <rdunlap@infradead.org>,
	kernel-hardening@lists.openwall.com,
	linux-hardening@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v8 3/6] stack: Optionally randomize kernel stack offset each syscall
Date: Wed, 31 Mar 2021 23:31:39 -0700	[thread overview]
Message-ID: <202103312329.394CCA13CF@keescook> (raw)
In-Reply-To: <87v9973q54.ffs@nanos.tec.linutronix.de>

On Thu, Apr 01, 2021 at 12:38:31AM +0200, Thomas Gleixner wrote:
> On Wed, Mar 31 2021 at 14:54, Kees Cook wrote:
> > On Wed, Mar 31, 2021 at 09:53:26AM +0200, Thomas Gleixner wrote:
> >> On Tue, Mar 30 2021 at 13:57, Kees Cook wrote:
> >> > +/*
> >> > + * Do not use this anywhere else in the kernel. This is used here because
> >> > + * it provides an arch-agnostic way to grow the stack with correct
> >> > + * alignment. Also, since this use is being explicitly masked to a max of
> >> > + * 10 bits, stack-clash style attacks are unlikely. For more details see
> >> > + * "VLAs" in Documentation/process/deprecated.rst
> >> > + * The asm statement is designed to convince the compiler to keep the
> >> > + * allocation around even after "ptr" goes out of scope.
> >> 
> >> Nit. That explanation of "ptr" might be better placed right at the
> >> add_random...() macro.
> >
> > Ah, yes! Fixed in v9.
> 
> Hmm, looking at V9 the "ptr" thing got lost ....

I put the comment inline in the macro directly above the asm().

> > Do you want to take this via -tip (and leave off the arm64 patch until
> > it is acked), or would you rather it go via arm64? (I've sent v9 now...)
> 
> Either way is fine.

Since the arm64 folks have been a bit busy, can you just put this in
-tip and leave off the arm64 patch for now?

Thanks!

-- 
Kees Cook

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2021-04-01  6:32 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-30 20:57 [PATCH v8 0/6] Optionally randomize kernel stack offset each syscall Kees Cook
2021-03-30 20:57 ` Kees Cook
2021-03-30 20:57 ` [PATCH v8 1/6] jump_label: Provide CONFIG-driven build state defaults Kees Cook
2021-03-30 20:57   ` Kees Cook
2021-03-30 20:57 ` [PATCH v8 2/6] init_on_alloc: Optimize static branches Kees Cook
2021-03-30 20:57   ` Kees Cook
2021-03-30 20:57 ` [PATCH v8 3/6] stack: Optionally randomize kernel stack offset each syscall Kees Cook
2021-03-30 20:57   ` Kees Cook
2021-03-31  7:53   ` Thomas Gleixner
2021-03-31  7:53     ` Thomas Gleixner
2021-03-31 21:54     ` Kees Cook
2021-03-31 21:54       ` Kees Cook
2021-03-31 22:38       ` Thomas Gleixner
2021-03-31 22:38         ` Thomas Gleixner
2021-04-01  6:31         ` Kees Cook [this message]
2021-04-01  6:31           ` Kees Cook
2021-04-01  8:30   ` Will Deacon
2021-04-01  8:30     ` Will Deacon
2021-04-01 11:15     ` David Laight
2021-04-01 11:15       ` David Laight
2021-04-01 22:42       ` Kees Cook
2021-04-01 22:42         ` Kees Cook
2021-03-30 20:57 ` [PATCH v8 4/6] x86/entry: Enable random_kstack_offset support Kees Cook
2021-03-30 20:57   ` Kees Cook
2021-03-31  7:50   ` Thomas Gleixner
2021-03-31  7:50     ` Thomas Gleixner
2021-03-30 20:57 ` [PATCH v8 5/6] arm64: entry: " Kees Cook
2021-03-30 20:57   ` Kees Cook
2021-03-30 20:57 ` [PATCH v8 6/6] lkdtm: Add REPORT_STACK for checking stack offsets Kees Cook
2021-03-30 20:57   ` Kees Cook
2021-04-01 19:17 ` [PATCH] Where we are for this patch? Roy Yang
2021-04-01 19:17   ` Roy Yang
2021-04-01 19:48   ` Al Viro
2021-04-01 19:48     ` Al Viro
2021-04-01 20:13     ` Theodore Ts'o
2021-04-01 20:13       ` Theodore Ts'o
2021-04-01 21:46   ` [PATCH v8 0/6] Optionally randomize kernel stack offset each syscall Kees Cook
2021-04-01 21:46     ` Kees Cook

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