From 8a5e5e02fc83aaf67053ab53b359af08c6c49aaf Mon Sep 17 00:00:00 2001 From: Vasily Kulikov Date: Wed, 9 Sep 2015 15:36:00 -0700 Subject: include/linux/poison.h: fix LIST_POISON{1,2} offset Poison pointer values should be small enough to find a room in non-mmap'able/hardly-mmap'able space. E.g. on x86 "poison pointer space" is located starting from 0x0. Given unprivileged users cannot mmap anything below mmap_min_addr, it should be safe to use poison pointers lower than mmap_min_addr. The current poison pointer values of LIST_POISON{1,2} might be too big for mmap_min_addr values equal or less than 1 MB (common case, e.g. Ubuntu uses only 0x10000). There is little point to use such a big value given the "poison pointer space" below 1 MB is not yet exhausted. Changing it to a smaller value solves the problem for small mmap_min_addr setups. The values are suggested by Solar Designer: http://www.openwall.com/lists/oss-security/2015/05/02/6 Signed-off-by: Vasily Kulikov Cc: Solar Designer Cc: Thomas Gleixner Cc: "Kirill A. Shutemov" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/poison.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/poison.h b/include/linux/poison.h index 2110a81..253c9b4 100644 --- a/include/linux/poison.h +++ b/include/linux/poison.h @@ -19,8 +19,8 @@ * under normal circumstances, used to verify that nobody uses * non-initialized list entries. */ -#define LIST_POISON1 ((void *) 0x00100100 + POISON_POINTER_DELTA) -#define LIST_POISON2 ((void *) 0x00200200 + POISON_POINTER_DELTA) +#define LIST_POISON1 ((void *) 0x100 + POISON_POINTER_DELTA) +#define LIST_POISON2 ((void *) 0x200 + POISON_POINTER_DELTA) /********** include/linux/timer.h **********/ /* -- cgit v1.1