[kernel-hardening] [PATCH 3/7] ARM: Use simpler API for random address requests

From: Jason Cooper <jason@lakedaemon.net>
To: william.c.roberts@intel.com, Yann Droneaud <ydroneaud@opteya.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	kernel-hardening@lists.openwall.com
Cc: linux@arm.linux.org.uk, akpm@linux-foundation.org,
	keescook@chromium.org, tytso@mit.edu, arnd@arndb.de,
	gregkh@linuxfoundation.org, catalin.marinas@arm.com,
	will.deacon@arm.com, ralf@linux-mips.org,
	benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au,
	davem@davemloft.net, tglx@linutronix.de, mingo@redhat.com,
	hpa@zytor.com, x86@kernel.org, viro@zeniv.linux.org.uk,
	nnk@google.com, jeffv@google.com, dcashman@android.com,
	Jason Cooper <jason@lakedaemon.net>
Subject: [kernel-hardening] [PATCH 3/7] ARM: Use simpler API for random address requests
Date: Thu, 28 Jul 2016 20:47:26 +0000	[thread overview]
Message-ID: <20160728204730.27453-4-jason@lakedaemon.net> (raw)
In-Reply-To: <20160728204730.27453-1-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>
---
 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..02dee671cded 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_addr(mm->brk, 0x02000000);
 }
 
 #ifdef CONFIG_MMU
-- 
2.9.2
