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From: Keith Packard <keithpac@amazon.com>
To: linux-kernel@vger.kernel.org
Cc: "Abbott Liu" <liuwenliang@huawei.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Andrey Ryabinin" <ryabinin.a.a@gmail.com>,
	"Anshuman Khandual" <anshuman.khandual@arm.com>,
	"Ard Biesheuvel" <ardb@kernel.org>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Bjorn Andersson" <bjorn.andersson@linaro.org>,
	"Christoph Lameter" <cl@linux.com>,
	"Dennis Zhou" <dennis@kernel.org>,
	"Geert Uytterhoeven" <geert+renesas@glider.be>,
	"Jens Axboe" <axboe@kernel.dk>, "Joe Perches" <joe@perches.com>,
	"Kees Cook" <keescook@chromium.org>,
	"Keith Packard" <keithpac@amazon.com>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski@canonical.com>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
	"Manivannan Sadhasivam" <mani@kernel.org>,
	"Marc Zyngier" <maz@kernel.org>,
	"Masahiro Yamada" <masahiroy@kernel.org>,
	"Mike Rapoport" <rppt@kernel.org>,
	"Nathan Chancellor" <nathan@kernel.org>,
	"Nick Desaulniers" <ndesaulniers@google.com>,
	"Nick Desaulniers" <ndesaulniers@gooogle.com>,
	"Nicolas Pitre" <nico@fluxnic.net>,
	"Russell King" <linux@armlinux.org.uk>,
	"Tejun Heo" <tj@kernel.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Valentin Schneider" <valentin.schneider@arm.com>,
	"Viresh Kumar" <viresh.kumar@linaro.org>,
	"Wolfram Sang (Renesas)" <wsa+renesas@sang-engineering.com>,
	"YiFei Zhu" <yifeifz2@illinois.edu>
Subject: [PATCH 0/7] ARM: support THREAD_INFO_IN_TASK (v3)
Date: Tue,  7 Sep 2021 15:00:31 -0700	[thread overview]
Message-ID: <20210907220038.91021-1-keithpac@amazon.com> (raw)
In-Reply-To: <20210904060908.1310204-1-keithp@keithp.com>

Placing thread_info in the kernel stack leaves it vulnerable to stack
overflow attacks. This short series addresses that by using the
existing THREAD_INFO_IN_TASK infrastructure.

This is the third version of this series, in this version the changes
are restricted to hardware which provides the TPIDRPRW register. This
register is repurposed from holding the per_cpu_offset value to
holding the 'current' value as that allows fetching this value
atomically so that it can be used in a preemptable context.

The series is broken into seven pieces:

 1) Change the secondary_start_kernel API to receive the cpu
    number. This avoids needing to be able to find this value independently in
    future patches.

 2) Change the secondary_start_kernel API to also receive the 'task'
    value. Passing the value to this function also avoids needing to
    be able to discover it independently.

 3) A cleanup which avoids assuming that THREAD_INFO_IN_TASK is not set.

 4) A hack, borrowed from the powerpc arch, which allows locating the 'cpu'
    field in either thread_info or task_struct, without requiring linux/sched.h
    to be included in asm/smp.h

 5) Disable the optimization storing per_cpu_offset in TPIDRPRW. This leaves
    the register free to hold 'current' instead.

 6) Use TPIDRPRW for 'current'. This is enabled for either CPU_V6K or CPU_V7,
    but not if CPU_V6 is also enabled.

 7) Enable THREAD_INFO_IN_TASK whenever TPIDRPRW is used to hold 'current'.

Signed-off-by: Keith Packard <keithpac@amazon.com>



WARNING: multiple messages have this Message-ID (diff)
From: Keith Packard <keithpac@amazon.com>
To: linux-kernel@vger.kernel.org
Cc: "Abbott Liu" <liuwenliang@huawei.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Andrey Ryabinin" <ryabinin.a.a@gmail.com>,
	"Anshuman Khandual" <anshuman.khandual@arm.com>,
	"Ard Biesheuvel" <ardb@kernel.org>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Bjorn Andersson" <bjorn.andersson@linaro.org>,
	"Christoph Lameter" <cl@linux.com>,
	"Dennis Zhou" <dennis@kernel.org>,
	"Geert Uytterhoeven" <geert+renesas@glider.be>,
	"Jens Axboe" <axboe@kernel.dk>, "Joe Perches" <joe@perches.com>,
	"Kees Cook" <keescook@chromium.org>,
	"Keith Packard" <keithpac@amazon.com>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski@canonical.com>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
	"Manivannan Sadhasivam" <mani@kernel.org>,
	"Marc Zyngier" <maz@kernel.org>,
	"Masahiro Yamada" <masahiroy@kernel.org>,
	"Mike Rapoport" <rppt@kernel.org>,
	"Nathan Chancellor" <nathan@kernel.org>,
	"Nick Desaulniers" <ndesaulniers@google.com>,
	"Nick Desaulniers" <ndesaulniers@gooogle.com>,
	"Nicolas Pitre" <nico@fluxnic.net>,
	"Russell King" <linux@armlinux.org.uk>,
	"Tejun Heo" <tj@kernel.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Valentin Schneider" <valentin.schneider@arm.com>,
	"Viresh Kumar" <viresh.kumar@linaro.org>,
	"Wolfram Sang (Renesas)" <wsa+renesas@sang-engineering.com>,
	"YiFei Zhu" <yifeifz2@illinois.edu>
Subject: [PATCH 0/7] ARM: support THREAD_INFO_IN_TASK (v3)
Date: Tue,  7 Sep 2021 15:00:31 -0700	[thread overview]
Message-ID: <20210907220038.91021-1-keithpac@amazon.com> (raw)
In-Reply-To: <20210904060908.1310204-1-keithp@keithp.com>

Placing thread_info in the kernel stack leaves it vulnerable to stack
overflow attacks. This short series addresses that by using the
existing THREAD_INFO_IN_TASK infrastructure.

This is the third version of this series, in this version the changes
are restricted to hardware which provides the TPIDRPRW register. This
register is repurposed from holding the per_cpu_offset value to
holding the 'current' value as that allows fetching this value
atomically so that it can be used in a preemptable context.

The series is broken into seven pieces:

 1) Change the secondary_start_kernel API to receive the cpu
    number. This avoids needing to be able to find this value independently in
    future patches.

 2) Change the secondary_start_kernel API to also receive the 'task'
    value. Passing the value to this function also avoids needing to
    be able to discover it independently.

 3) A cleanup which avoids assuming that THREAD_INFO_IN_TASK is not set.

 4) A hack, borrowed from the powerpc arch, which allows locating the 'cpu'
    field in either thread_info or task_struct, without requiring linux/sched.h
    to be included in asm/smp.h

 5) Disable the optimization storing per_cpu_offset in TPIDRPRW. This leaves
    the register free to hold 'current' instead.

 6) Use TPIDRPRW for 'current'. This is enabled for either CPU_V6K or CPU_V7,
    but not if CPU_V6 is also enabled.

 7) Enable THREAD_INFO_IN_TASK whenever TPIDRPRW is used to hold 'current'.

Signed-off-by: Keith Packard <keithpac@amazon.com>



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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2021-09-07 22:00 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-02 15:54 [PATCH 0/2]: ARM: Enable THREAD_INFO_IN_TASK Keith Packard
2021-09-02 15:54 ` Keith Packard
2021-09-02 15:54 ` [PATCH 1/2] ARM: Add per-cpu variable holding cpu number Keith Packard
2021-09-02 15:54   ` Keith Packard
2021-09-02 15:54 ` [PATCH 2/2] ARM: Move thread_info into task_struct Keith Packard
2021-09-02 15:54   ` Keith Packard
2021-09-02 16:07 ` [PATCH 0/2]: ARM: Enable THREAD_INFO_IN_TASK Kees Cook
2021-09-02 16:07   ` Kees Cook
2021-09-02 16:18   ` Ard Biesheuvel
2021-09-02 16:18     ` Ard Biesheuvel
2021-09-02 17:37     ` Kees Cook
2021-09-02 17:37       ` Kees Cook
2021-09-02 16:54   ` Russell King (Oracle)
2021-09-02 16:54     ` Russell King (Oracle)
2021-09-02 16:53 ` Russell King (Oracle)
2021-09-02 16:53   ` Russell King (Oracle)
2021-09-02 17:35   ` Kees Cook
2021-09-02 17:35     ` Kees Cook
2021-09-02 17:58   ` Keith Packard
2021-09-02 17:58     ` Keith Packard
2021-09-04  6:09 ` [PATCH 0/2] ARM: support THREAD_INFO_IN_TASK (v7 only) (v2) Keith Packard
2021-09-04  6:09   ` Keith Packard
2021-09-04  6:09   ` [PATCH 1/3] ARM: Pass cpu number to secondary_start_kernel Keith Packard
2021-09-04  6:09     ` Keith Packard
2021-09-05 20:25     ` Ard Biesheuvel
2021-09-05 20:25       ` Ard Biesheuvel
2021-09-04  6:09   ` [PATCH 2/3] ARM: Move thread_info into task_struct (v7 only) Keith Packard
2021-09-04  6:09     ` Keith Packard
2021-09-05 20:56     ` Ard Biesheuvel
2021-09-05 20:56       ` Ard Biesheuvel
2021-09-06  6:14       ` Keith Packard
2021-09-06  6:14         ` Keith Packard
2021-09-06  7:49         ` Ard Biesheuvel
2021-09-06  7:49           ` Ard Biesheuvel
2021-09-07 15:24           ` Keith Packard
2021-09-07 15:24             ` Keith Packard
2021-09-07 16:05             ` Ard Biesheuvel
2021-09-07 16:05               ` Ard Biesheuvel
2021-09-07 22:17               ` Keith Packard
2021-09-07 22:17                 ` Keith Packard
2021-09-06  6:20       ` Keith Packard
2021-09-06  6:20         ` Keith Packard
2021-09-04  6:09   ` [PATCH 3/3] ARM: Add per-cpu variable cpu_number " Keith Packard
2021-09-04  6:09     ` Keith Packard
2021-09-07 22:00   ` Keith Packard [this message]
2021-09-07 22:00     ` [PATCH 0/7] ARM: support THREAD_INFO_IN_TASK (v3) Keith Packard
2021-09-07 22:00     ` [PATCH 1/7] ARM: Pass cpu number to secondary_start_kernel Keith Packard
2021-09-07 22:00       ` Keith Packard
2021-09-07 22:00     ` [PATCH 2/7] ARM: Pass task " Keith Packard
2021-09-07 22:00       ` Keith Packard
2021-09-07 22:00     ` [PATCH 3/7] ARM: Use smp_processor_id() in vfp_pm_suspend instead of ti->cpu Keith Packard
2021-09-07 22:00       ` Keith Packard
2021-09-07 22:00     ` [PATCH 4/7] ARM: Use hack from powerpc to get current cpu number Keith Packard
2021-09-07 22:00       ` Keith Packard
2021-09-08  7:45       ` Ard Biesheuvel
2021-09-08  7:45         ` Ard Biesheuvel
2021-09-07 22:00     ` [PATCH 5/7] ARM: Stop using TPIDRPRW to hold per_cpu_offset Keith Packard
2021-09-07 22:00       ` Keith Packard
2021-09-09 13:54       ` Ard Biesheuvel
2021-09-09 13:54         ` Ard Biesheuvel
2021-09-07 22:00     ` [PATCH 6/7] ARM: Use TPIDRPRW for current Keith Packard
2021-09-07 22:00       ` Keith Packard
2021-09-09 13:56       ` Ard Biesheuvel
2021-09-09 13:56         ` Ard Biesheuvel
2021-09-07 22:00     ` [PATCH 7/7] ARM: Move thread_info into task_struct (v7 only) Keith Packard
2021-09-07 22:00       ` Keith Packard
2021-09-08  7:01     ` [PATCH 0/7] ARM: support THREAD_INFO_IN_TASK (v3) Krzysztof Kozlowski
2021-09-08  7:01       ` Krzysztof Kozlowski
2021-09-08  7:47       ` Ard Biesheuvel
2021-09-08  7:47         ` Ard Biesheuvel
2021-09-08  7:50         ` Geert Uytterhoeven
2021-09-08  7:50           ` Geert Uytterhoeven

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