linux-kernel - [PATCH v2 04/15] x86, kaslr: get kaslr

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Date:	Wed,  4 Mar 2015 00:00:37 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Matt Fleming <matt.fleming@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Jiri Kosina <jkosina@...e.cz>,
	Borislav Petkov <bp@...e.de>, Baoquan He <bhe@...hat.com>,
	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
	linux-pci@...r.kernel.org, Yinghai Lu <yinghai@...nel.org>,
	Kees Cook <keescook@...omium.org>
Subject: [PATCH v2 04/15] x86, kaslr: get kaslr_enabled back correctly

commit f47233c2d34f ("x86/mm/ASLR: Propagate base load address calculation")
is using address as value for kaslr_enabled.

That will random kaslr_enabled get that set or cleared.
Will have problem for system really have kaslr enabled.

-v2: update changelog.

Fixes: f47233c2d34f ("x86/mm/ASLR: Propagate base load address calculation")
Cc: Matt Fleming <matt.fleming@...el.com>
Cc: Borislav Petkov <bp@...e.de>
Cc: Kees Cook <keescook@...omium.org>
Cc: Jiri Kosina <jkosina@...e.cz>
Acked-by: Jiri Kosina <jkosina@...e.cz>
Signed-off-by: Yinghai Lu <yinghai@...nel.org>
---
 arch/x86/kernel/setup.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 98dc931..05d444f 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -429,7 +429,13 @@ static void __init reserve_initrd(void)
 
 static void __init parse_kaslr_setup(u64 pa_data, u32 data_len)
 {
-	kaslr_enabled = (bool)(pa_data + sizeof(struct setup_data));
+	/* kaslr_setup_data is defined in aslr.c */
+	unsigned char *data;
+	unsigned long offset = sizeof(struct setup_data);
+
+	data = early_memremap(pa_data, offset + 1);
+	kaslr_enabled = *(data + offset);
+	early_memunmap(data, offset + 1);
 }
 
 static void __init parse_setup_data(void)
-- 
1.8.4.5

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