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Commit 1f0569df authored by Kees Cook's avatar Kees Cook Committed by Linus Torvalds
Browse files

mips: extract logic for mmap_rnd() 



In preparation for splitting out ET_DYN ASLR, extract the mmap ASLR
selection into a separate function.

Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent dd04cff1

arch/mips/mm/mmap.c

+16 −8
Original line number Diff line number Diff line
@@ -142,19 +142,27 @@ unsigned long arch_get_unmapped_area_topdown(struct file *filp, 
			addr0, len, pgoff, flags, DOWN);

}



void arch_pick_mmap_layout(struct mm_struct *mm)

static unsigned long mmap_rnd(void)

{

	unsigned long random_factor = 0UL;

	unsigned long rnd;



	if (current->flags & PF_RANDOMIZE) {

		random_factor = get_random_int();

		random_factor = random_factor << PAGE_SHIFT;

	rnd = (unsigned long)get_random_int();

	rnd <<= PAGE_SHIFT;

	if (TASK_IS_32BIT_ADDR)

			random_factor &= 0xfffffful;

		rnd &= 0xfffffful;

	else

			random_factor &= 0xffffffful;

		rnd &= 0xffffffful;



	return rnd;

}



void arch_pick_mmap_layout(struct mm_struct *mm)

{

	unsigned long random_factor = 0UL;



	if (current->flags & PF_RANDOMIZE)

		random_factor = mmap_rnd();



	if (mmap_is_legacy()) {

		mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;

		mm->get_unmapped_area = arch_get_unmapped_area;