Re: [PATCH 1/5] arm: factor out mmap ASLR into mmap_rnd
From: Russell King - ARM Linux <hidden>
Date: 2015-03-09 14:48:31
Also in:
linux-arm-kernel, linux-fsdevel, linux-mips, lkml
On Mon, Mar 02, 2015 at 04:19:44PM -0800, Kees Cook wrote:
In preparation for exporting per-arch mmap randomization functions, this moves the ASLR calculations for mmap on ARM into a separate routine. Signed-off-by: Kees Cook <redacted>
Looks fine, thanks. Acked-by: Russell King <redacted>
quoted hunk ↗ jump to hunk
--- arch/arm/mm/mmap.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c index 5e85ed371364..0f8bc158f2c6 100644 --- a/arch/arm/mm/mmap.c +++ b/arch/arm/mm/mmap.c@@ -169,14 +169,21 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, return addr; } -void arch_pick_mmap_layout(struct mm_struct *mm) +static unsigned long mmap_rnd(void) { - unsigned long random_factor = 0UL; + unsigned long rnd = 0UL; /* 8 bits of randomness in 20 address space bits */ if ((current->flags & PF_RANDOMIZE) && !(current->personality & ADDR_NO_RANDOMIZE)) - random_factor = (get_random_int() % (1 << 8)) << PAGE_SHIFT; + rnd = (get_random_int() % (1 << 8)) << PAGE_SHIFT; + + return rnd; +} + +void arch_pick_mmap_layout(struct mm_struct *mm) +{ + unsigned long random_factor = mmap_rnd(); if (mmap_is_legacy()) { mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;-- 1.9.1
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