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[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>
This commit is contained in:
Heiko Carstens 2011-01-12 09:55:30 +01:00 committed by Martin Schwidefsky
parent a05c90f194
commit 3351918282
2 changed files with 21 additions and 0 deletions
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3
arch/s390/include/asm/elf.h
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@ -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

18
arch/s390/kernel/process.c
View File

@ -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;
}