[S390] Randomise the brk region
Randomize heap address like other architectures do already.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 38ff69e..26d48fe 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -341,3 +341,21 @@
sp -= get_random_int() & ~PAGE_MASK;
return sp & ~0xf;
}
+
+static inline unsigned long brk_rnd(void)
+{
+ /* 8MB for 32bit, 1GB for 64bit */
+ if (is_32bit_task())
+ return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
+ else
+ return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT;
+}
+
+unsigned long arch_randomize_brk(struct mm_struct *mm)
+{
+ unsigned long ret = PAGE_ALIGN(mm->brk + brk_rnd());
+
+ if (ret < mm->brk)
+ return mm->brk;
+ return ret;
+}