x86: use simpler API for random address requests (9c6f0902) · Commits · 戴 / test

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 <jason@lakedaemon.net> Acked-by:

Kees Cook <keescook@chromium.org> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H . Peter Anvin" <hpa@zytor.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/kernel/process.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -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);
		}

		/*

arch/x86/kernel/sys_x86_64.c

+1 −4

Original line number	Diff line number	Diff line
		@@ -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;

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