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46 lines
1.9 KiB
Diff
46 lines
1.9 KiB
Diff
From 8a5e5e02fc83aaf67053ab53b359af08c6c49aaf Mon Sep 17 00:00:00 2001
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From: Vasily Kulikov <segoon@openwall.com>
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Date: Wed, 9 Sep 2015 15:36:00 -0700
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Subject: [PATCH] include/linux/poison.h: fix LIST_POISON{1,2} offset
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Poison pointer values should be small enough to find a room in
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non-mmap'able/hardly-mmap'able space. E.g. on x86 "poison pointer space"
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is located starting from 0x0. Given unprivileged users cannot mmap
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anything below mmap_min_addr, it should be safe to use poison pointers
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lower than mmap_min_addr.
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The current poison pointer values of LIST_POISON{1,2} might be too big for
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mmap_min_addr values equal or less than 1 MB (common case, e.g. Ubuntu
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uses only 0x10000). There is little point to use such a big value given
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the "poison pointer space" below 1 MB is not yet exhausted. Changing it
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to a smaller value solves the problem for small mmap_min_addr setups.
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The values are suggested by Solar Designer:
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http://www.openwall.com/lists/oss-security/2015/05/02/6
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Signed-off-by: Vasily Kulikov <segoon@openwall.com>
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Cc: Solar Designer <solar@openwall.com>
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Cc: Thomas Gleixner <tglx@linutronix.de>
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Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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---
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include/linux/poison.h | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/include/linux/poison.h b/include/linux/poison.h
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index 2110a81c5e2af..253c9b4198eff 100644
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--- a/include/linux/poison.h
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+++ b/include/linux/poison.h
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@@ -19,8 +19,8 @@
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* under normal circumstances, used to verify that nobody uses
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* non-initialized list entries.
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*/
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-#define LIST_POISON1 ((void *) 0x00100100 + POISON_POINTER_DELTA)
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-#define LIST_POISON2 ((void *) 0x00200200 + POISON_POINTER_DELTA)
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+#define LIST_POISON1 ((void *) 0x100 + POISON_POINTER_DELTA)
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+#define LIST_POISON2 ((void *) 0x200 + POISON_POINTER_DELTA)
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/********** include/linux/timer.h **********/
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/*
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