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authorHeiko Carstens <heiko.carstens@de.ibm.com>2011-01-12 09:55:27 +0100
committerMartin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com>2011-01-12 09:55:25 +0100
commitdf1ca53cba34b1d40a4ed47907d71397e4ee72c2 (patch)
treecbfc440a178eaadbfea7af7dbf0b2d69dec48a1b /arch/s390
parent1060f62ea47e609b0c1672e8d1ac216e57f11a8e (diff)
downloadlinux-linaro-android-df1ca53cba34b1d40a4ed47907d71397e4ee72c2.tar.gz
[S390] Randomize mmap start address
Randomize mmap start address with 8MB. 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/mm/mmap.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index 74d663f367e..c9a9f7f1818 100644
--- a/arch/s390/mm/mmap.c
+++ b/arch/s390/mm/mmap.c
@@ -27,6 +27,7 @@
#include <linux/personality.h>
#include <linux/mm.h>
#include <linux/module.h>
+#include <linux/random.h>
#include <asm/pgalloc.h>
#include <asm/compat.h>
@@ -56,6 +57,14 @@ static inline int mmap_is_legacy(void)
return sysctl_legacy_va_layout;
}
+static unsigned long mmap_rnd(void)
+{
+ if (!(current->flags & PF_RANDOMIZE))
+ return 0;
+ /* 8MB randomization for mmap_base */
+ return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
+}
+
static inline unsigned long mmap_base(void)
{
unsigned long gap = rlimit(RLIMIT_STACK);
@@ -64,8 +73,8 @@ static inline unsigned long mmap_base(void)
gap = MIN_GAP;
else if (gap > MAX_GAP)
gap = MAX_GAP;
-
- return STACK_TOP - stack_maxrandom_size() - (gap & PAGE_MASK);
+ gap &= PAGE_MASK;
+ return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap;
}
#ifndef CONFIG_64BIT