This is a note to let you know that I've just added the patch titled
ARM: poison the vectors page
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm-poison-the-vectors-page.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f928d4f2a86f46b030fa0850385b4391fc2b5918 Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Date: Thu, 4 Jul 2013 11:00:23 +0100
Subject: ARM: poison the vectors page
From: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
commit f928d4f2a86f46b030fa0850385b4391fc2b5918 upstream.
Fill the empty regions of the vectors page with an exception generating
instruction. This ensures that any inappropriate branch to the vector
page is appropriately trapped, rather than just encountering some code
to execute. (The vectors page was filled with zero before, which
corresponds with the "andeq r0, r0, r0" instruction - a no-op.)
Acked-by Nicolas Pitre <nico@xxxxxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/kernel/traps.c | 10 ++++++++++
1 file changed, 10 insertions(+)
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -793,10 +793,20 @@ void __init early_trap_init(void *vector
extern char __vectors_start[], __vectors_end[];
extern char __kuser_helper_start[], __kuser_helper_end[];
int kuser_sz = __kuser_helper_end - __kuser_helper_start;
+ unsigned i;
vectors_page = vectors_base;
/*
+ * Poison the vectors page with an undefined instruction. This
+ * instruction is chosen to be undefined for both ARM and Thumb
+ * ISAs. The Thumb version is an undefined instruction with a
+ * branch back to the undefined instruction.
+ */
+ for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
+ ((u32 *)vectors_base)[i] = 0xe7fddef1;
+
+ /*
* Copy the vectors, stubs and kuser helpers (in entry-armv.S)
* into the vector page, mapped at 0xffff0000, and ensure these
* are visible to the instruction stream.
Patches currently in stable-queue which might be from rmk+kernel@xxxxxxxxxxxxxxxx are
queue-3.4/arm-move-vector-stubs.patch
queue-3.4/arm-use-linker-magic-for-vectors-and-vector-stubs.patch
queue-3.4/arm-make-vectors-page-inaccessible-from-userspace.patch
queue-3.4/arm-allow-kuser-helpers-to-be-removed-from-the-vector-page.patch
queue-3.4/arm-poison-the-vectors-page.patch
queue-3.4/arm-update-fiq-support-for-relocation-of-vectors.patch
queue-3.4/arm-poison-memory-between-kuser-helpers.patch
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