linux-kernel - [RFC patch 2/6] x86: Use simpler API for random address requests

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20160726030201.6775-2-jason@lakedaemon.net>
Date:	Tue, 26 Jul 2016 03:01:56 +0000
From:	Jason Cooper <jason@...edaemon.net>
To:	william.c.roberts@...el.com, linux-mm@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com
Cc:	Jason Cooper <jason@...edaemon.net>, linux@....linux.org.uk,
	akpm@...ux-foundation.org, keescook@...omium.org, tytso@....edu,
	arnd@...db.de, gregkh@...uxfoundation.org, catalin.marinas@....com,
	will.deacon@....com, ralf@...ux-mips.org, benh@...nel.crashing.org,
	paulus@...ba.org, mpe@...erman.id.au, davem@...emloft.net,
	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	x86@...nel.org, viro@...iv.linux.org.uk, nnk@...gle.com,
	jeffv@...gle.com, alyzyn@...roid.com, dcashman@...roid.com
Subject: [RFC patch 2/6] 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.

Signed-off-by: Jason Cooper <jason@...edaemon.net>
---
 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 96becbbb52e0..a083a2c0744e 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -507,8 +507,7 @@ 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_addr(mm->brk, 0x02000000);
 }
 
 /*
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index 10e0272d789a..f9cad22808fc 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_addr(*begin, 0x02000000);
 		}
 	} else {
 		*begin = current->mm->mmap_legacy_base;
-- 
2.9.2