linux-kernel - [PATCH v2] ARM: mm: fix location of

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Message-ID: <20160615202447.GA5005@www.outflux.net>
Date:	Wed, 15 Jun 2016 13:24:47 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Russell King <linux@...linux.org.uk>
Cc:	linux-kernel@...r.kernel.org,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Matt Fleming <matt@...eblueprint.co.uk>,
	Pratyush Anand <panand@...hat.com>,
	Nicolas Pitre <nicolas.pitre@...aro.org>,
	Vladimir Murzin <vladimir.murzin@....com>,
	Toshi Kani <toshi.kani@....com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Chris Brandt <chris.brandt@...esas.com>,
	Alexander Potapenko <glider@...gle.com>,
	Marc Zyngier <marc.zyngier@....com>,
	Arnd Bergmann <arnd@...db.de>,
	linux-arm-kernel@...ts.infradead.org
Subject: [PATCH v2] ARM: mm: fix location of _etext

The _etext position is defined to be the end of the kernel text code,
and should not include any part of the data segments. This interferes
with things that might check memory ranges and expect executable code
up to _etext. Just to be conservative, leave the kernel resource as
it was, using __init_begin instead of _etext as the end mark.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
v2:
- Switched resource tracker to using __init_begin, rmk
---
 arch/arm/kernel/setup.c       | 2 +-
 arch/arm/kernel/vmlinux.lds.S | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 7b5350060612..dd84f03dc2d4 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -844,7 +844,7 @@ static void __init request_standard_resources(const struct machine_desc *mdesc)
 	struct resource *res;
 
 	kernel_code.start   = virt_to_phys(_text);
-	kernel_code.end     = virt_to_phys(_etext - 1);
+	kernel_code.end     = virt_to_phys(__init_begin - 1);
 	kernel_data.start   = virt_to_phys(_sdata);
 	kernel_data.end     = virt_to_phys(_end - 1);
 
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index e2c6da096cef..99420fc1f066 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -125,6 +125,8 @@ SECTIONS
 #ifdef CONFIG_DEBUG_ALIGN_RODATA
 	. = ALIGN(1<<SECTION_SHIFT);
 #endif
+	_etext = .;			/* End of text section */
+
 	RO_DATA(PAGE_SIZE)
 
 	. = ALIGN(4);
@@ -155,8 +157,6 @@ SECTIONS
 
 	NOTES
 
-	_etext = .;			/* End of text and rodata section */
-
 #ifdef CONFIG_DEBUG_RODATA
 	. = ALIGN(1<<SECTION_SHIFT);
 #else
-- 
2.7.4


-- 
Kees Cook
Chrome OS & Brillo Security