From 9c6f0902a55226b08b9703408f04b258b9afa0bc Mon Sep 17 00:00:00 2001 From: Jason Cooper Date: Tue, 11 Oct 2016 13:53:56 -0700 Subject: [PATCH] x86: use simpler API for random address requests Currently, all callers to randomize_range() set the length to 0 and calculate end by adding a constant to the start address. We can simplify the API to remove a bunch of needless checks and variables. Use the new randomize_addr(start, range) call to set the requested address. Link: http://lkml.kernel.org/r/20160803233913.32511-3-jason@lakedaemon.net Signed-off-by: Jason Cooper Acked-by: Kees Cook Cc: "Theodore Ts'o" Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H . Peter Anvin" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86/kernel/process.c | 3 +-- arch/x86/kernel/sys_x86_64.c | 5 +---- 2 files changed, 2 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 28cea7802ecb..0888a879120f 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -509,8 +509,7 @@ unsigned long arch_align_stack(unsigned long sp) unsigned long arch_randomize_brk(struct mm_struct *mm) { - unsigned long range_end = mm->brk + 0x02000000; - return randomize_range(mm->brk, range_end, 0) ? : mm->brk; + return randomize_page(mm->brk, 0x02000000); } /* diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c index 10e0272d789a..a55ed63b9f91 100644 --- a/arch/x86/kernel/sys_x86_64.c +++ b/arch/x86/kernel/sys_x86_64.c @@ -101,7 +101,6 @@ static void find_start_end(unsigned long flags, unsigned long *begin, unsigned long *end) { if (!test_thread_flag(TIF_ADDR32) && (flags & MAP_32BIT)) { - unsigned long new_begin; /* This is usually used needed to map code in small model, so it needs to be in the first 31bit. Limit it to that. This means we need to move the @@ -112,9 +111,7 @@ static void find_start_end(unsigned long flags, unsigned long *begin, *begin = 0x40000000; *end = 0x80000000; if (current->flags & PF_RANDOMIZE) { - new_begin = randomize_range(*begin, *begin + 0x02000000, 0); - if (new_begin) - *begin = new_begin; + *begin = randomize_page(*begin, 0x02000000); } } else { *begin = current->mm->mmap_legacy_base; -- 2.20.1