From 3351918282fd664e918a3175ddfae9b15656122e Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Wed, 12 Jan 2011 09:55:30 +0100 Subject: [PATCH] [S390] Randomise the brk region Randomize heap address like other architectures do already. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/include/asm/elf.h | 3 +++ arch/s390/kernel/process.c | 18 ++++++++++++++++++ 2 files changed, 21 insertions(+) diff --git a/arch/s390/include/asm/elf.h b/arch/s390/include/asm/elf.h index 9dbd3e7a3bc..457fb7c1623 100644 --- a/arch/s390/include/asm/elf.h +++ b/arch/s390/include/asm/elf.h @@ -220,4 +220,7 @@ struct linux_binprm; #define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1 int arch_setup_additional_pages(struct linux_binprm *, int); +extern unsigned long arch_randomize_brk(struct mm_struct *mm); +#define arch_randomize_brk arch_randomize_brk + #endif diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c index 38ff69e562c..26d48fe7299 100644 --- a/arch/s390/kernel/process.c +++ b/arch/s390/kernel/process.c @@ -341,3 +341,21 @@ unsigned long arch_align_stack(unsigned long sp) 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; +}