From 1f0569df0b0285e7ec2432d804a4921b06a61618 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Tue, 14 Apr 2015 15:47:51 -0700 Subject: [PATCH] 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: Kees Cook Reviewed-by: Ingo Molnar Cc: Ralf Baechle Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/mips/mm/mmap.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c index f1baadd..9a4f1f5 100644 --- a/arch/mips/mm/mmap.c +++ b/arch/mips/mm/mmap.c @@ -142,18 +142,26 @@ unsigned long arch_get_unmapped_area_topdown(struct file *filp, addr0, len, pgoff, flags, DOWN); } +static unsigned long mmap_rnd(void) +{ + unsigned long rnd; + + rnd = (unsigned long)get_random_int(); + rnd <<= PAGE_SHIFT; + if (TASK_IS_32BIT_ADDR) + rnd &= 0xfffffful; + else + 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 = get_random_int(); - random_factor = random_factor << PAGE_SHIFT; - if (TASK_IS_32BIT_ADDR) - random_factor &= 0xfffffful; - else - random_factor &= 0xffffffful; - } + if (current->flags & PF_RANDOMIZE) + random_factor = mmap_rnd(); if (mmap_is_legacy()) { mm->mmap_base = TASK_UNMAPPED_BASE + random_factor; -- 2.7.4