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Commit 652b14aa authored by David Daney's avatar David Daney Committed by Ralf Baechle
Browse files

MIPS: Enable heap randomization. 



Based somewhat on the PPC implementation.

32-bit processes have the heap randomized in an 8MB space, 256MB for
64-bit processes.

Signed-off-by: default avatarDavid Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1479/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 1091458d

arch/mips/include/asm/elf.h

+5 −0
Original line number Diff line number Diff line
@@ -372,4 +372,9 @@ extern const char *__elf_platform; 
struct linux_binprm;

extern int arch_setup_additional_pages(struct linux_binprm *bprm,

				       int uses_interp);



struct mm_struct;

extern unsigned long arch_randomize_brk(struct mm_struct *mm);

#define arch_randomize_brk arch_randomize_brk



#endif /* _ASM_ELF_H */

arch/mips/kernel/syscall.c

+28 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#include <linux/uaccess.h>

#include <linux/slab.h>

#include <linux/random.h>

#include <linux/elf.h>



#include <asm/asm.h>

#include <asm/branch.h>
@@ -153,6 +154,33 @@ void arch_pick_mmap_layout(struct mm_struct *mm) 
	mm->unmap_area = arch_unmap_area;

}



static inline unsigned long brk_rnd(void)

{

	unsigned long rnd = get_random_int();



	rnd = rnd << PAGE_SHIFT;

	/* 8MB for 32bit, 256MB for 64bit */

	if (TASK_IS_32BIT_ADDR)

		rnd = rnd & 0x7ffffful;

	else

		rnd = rnd & 0xffffffful;



	return rnd;

}



unsigned long arch_randomize_brk(struct mm_struct *mm)

{

	unsigned long base = mm->brk;

	unsigned long ret;



	ret = PAGE_ALIGN(base + brk_rnd());



	if (ret < mm->brk)

		return mm->brk;



	return ret;

}



SYSCALL_DEFINE6(mips_mmap, unsigned long, addr, unsigned long, len,

	unsigned long, prot, unsigned long, flags, unsigned long,

	fd, off_t, offset)