[PATCH v3 3/7] ARM: Use simpler API for random address requests

From: Jason Cooper <jason@lakedaemon.net>
To: Kees Cook <keescook@chromium.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	"Roberts, William C" <william.c.roberts@intel.com>,
	Yann Droneaud <ydroneaud@opteya.com>
Cc: "Linux-MM" <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"kernel-hardening" <kernel-hardening@lists.openwall.com>,
	"Russell King - ARM Linux" <linux@arm.linux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Theodore Ts'o" <tytso@mit.edu>, Arnd Bergmann <arnd@arndb.de>,
	gregkh@linuxfoundation.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Ralf Baechle <ralf@linux-mips.org>,
	benh@kernel.crashing.org, paulus@samba.org,
	"David S. Miller" <davem@davemloft.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, viro@zeniv.linux.org.uk,
	Nick Kralevich <nnk@google.com>,
	Jeffrey Vander Stoep <jeffv@google.com>,
	Daniel Cashman <dcashman@android.com>,
	Jason Cooper <jason@lakedaemon.net>
Subject: [PATCH v3 3/7] ARM: Use simpler API for random address requests
Date: Wed,  3 Aug 2016 23:39:09 +0000	[thread overview]
Message-ID: <20160803233913.32511-4-jason@lakedaemon.net> (raw)
In-Reply-To: <20160803233913.32511-1-jason@lakedaemon.net>

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.

Signed-off-by: Jason Cooper <jason@lakedaemon.net>
---
Changes from v2:
 - s/randomize_addr/randomize_page/ (Kees Cook)

 arch/arm/kernel/process.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 4a803c5a1ff7..3ee2fb4c9ae6 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -314,8 +314,7 @@ unsigned long get_wchan(struct task_struct *p)
 
 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);
 }
 
 #ifdef CONFIG_MMU
-- 
2.9.2
