linux-kernel - [PATCH] x86/mm: Fix personality(ADDR_NO

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Date:   Mon, 14 Aug 2017 18:57:19 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...capital.net>,
        Dmitry Safonov <dsafonov@...tuozzo.com>,
        Cyrill Gorcunov <gorcunov@...nvz.org>,
        Borislav Petkov <bp@...e.de>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        stable <stable@...r.kernel.org>
Subject: [PATCH] x86/mm: Fix personality(ADDR_NO_RANDOMIZE)

In v4.12, during rework of infrastructure around mmap_base, disable-ASLR
personality flag got accidentally broken.

Let's make it work again.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Fixes: 1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for 32-bit mmap()")
Cc: stable <stable@...r.kernel.org> [4.12+]
---
 arch/x86/mm/mmap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 229d04a83f85..779bdbe5e424 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -127,6 +127,8 @@ static unsigned long mmap_legacy_base(unsigned long rnd,
 static void arch_pick_mmap_base(unsigned long *base, unsigned long *legacy_base,
 		unsigned long random_factor, unsigned long task_size)
 {
+	if (!(current->flags & PF_RANDOMIZE))
+		random_factor = 0;
 	*legacy_base = mmap_legacy_base(random_factor, task_size);
 	if (mmap_is_legacy())
 		*base = *legacy_base;
-- 
2.14.1