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authorHeiko Carstens <heiko.carstens@de.ibm.com>2011-01-12 09:55:22 +0100
committerMartin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com>2011-01-12 09:55:24 +0100
commit9046e401e752dba784805a7818f99cc45a39cbff (patch)
tree0f05676ac01a7892b7fddf4e9f3a7e335c1f78d1 /arch/s390
parent7a63fa1a85d75756368d9c86fff5c1b193de991c (diff)
downloadlinux-linaro-android-9046e401e752dba784805a7818f99cc45a39cbff.tar.gz
[S390] mmap: consider stack address randomization
Consider stack address randomization when calulating mmap_base for flexible mmap layout . Because of address randomization the stack address can be up to 8MB lower than STACK_TOP. When calculating mmap_base this isn't taken into account, which could lead to the case that the gap between the real stack top and mmap_base is lower than what ulimit specifies for the maximum stack size. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390')
-rw-r--r--arch/s390/include/asm/elf.h2
-rw-r--r--arch/s390/mm/mmap.c11
2 files changed, 12 insertions, 1 deletions
diff --git a/arch/s390/include/asm/elf.h b/arch/s390/include/asm/elf.h
index 354d42616c7..9dbd3e7a3bc 100644
--- a/arch/s390/include/asm/elf.h
+++ b/arch/s390/include/asm/elf.h
@@ -206,6 +206,8 @@ do { \
current->mm->context.noexec == 0; \
})
+#define STACK_RND_MASK 0x7ffUL
+
#define ARCH_DLINFO \
do { \
if (vdso_enabled) \
diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index 869efbaed3e..5578740ab9c 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -30,6 +30,15 @@
#include <asm/pgalloc.h>
#include <asm/compat.h>
+static unsigned long stack_maxrandom_size(void)
+{
+ if (!(current->flags & PF_RANDOMIZE))
+ return 0;
+ if (current->personality & ADDR_NO_RANDOMIZE)
+ return 0;
+ return STACK_RND_MASK << PAGE_SHIFT;
+}
+
/*
* Top of mmap area (just below the process stack).
*
@@ -47,7 +56,7 @@ static inline unsigned long mmap_base(void)
else if (gap > MAX_GAP)
gap = MAX_GAP;
- return STACK_TOP - (gap & PAGE_MASK);
+ return STACK_TOP - stack_maxrandom_size() - (gap & PAGE_MASK);
}
static inline int mmap_is_legacy(void)