linux-kernel - [PATCH 3.16 216/357] x86/kaslr: Avoid the setup

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Message-Id: <20141003212940.013998664@linuxfoundation.org>
Date:	Fri,  3 Oct 2014 14:30:02 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Kees Cook <keescook@...omium.org>,
	Baoquan He <bhe@...hat.com>, Vivek Goyal <vgoyal@...hat.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Wei Yongjun <yongjun_wei@...ndmicro.com.cn>,
	Pavel Machek <pavel@....cz>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 3.16 216/357] x86/kaslr: Avoid the setup_data area when picking location

3.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kees Cook <keescook@...omium.org>

commit 0cacbfbeb5077b63d5d3cf6df88b14ac12ad584b upstream.

The KASLR location-choosing logic needs to avoid the setup_data
list memory areas as well. Without this, it would be possible to
have the ASLR position stomp on the memory, ultimately causing
the boot to fail.

Signed-off-by: Kees Cook <keescook@...omium.org>
Tested-by: Baoquan He <bhe@...hat.com>
Cc: Vivek Goyal <vgoyal@...hat.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Cc: Wei Yongjun <yongjun_wei@...ndmicro.com.cn>
Cc: Pavel Machek <pavel@....cz>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Link: http://lkml.kernel.org/r/20140911161931.GA12001@www.outflux.net
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/boot/compressed/aslr.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

--- a/arch/x86/boot/compressed/aslr.c
+++ b/arch/x86/boot/compressed/aslr.c
@@ -183,12 +183,27 @@ static void mem_avoid_init(unsigned long
 static bool mem_avoid_overlap(struct mem_vector *img)
 {
 	int i;
+	struct setup_data *ptr;

 	for (i = 0; i < MEM_AVOID_MAX; i++) {
 		if (mem_overlaps(img, &mem_avoid[i]))
 			return true;
 	}

+	/* Avoid all entries in the setup_data linked list. */
+	ptr = (struct setup_data *)(unsigned long)real_mode->hdr.setup_data;
+	while (ptr) {
+		struct mem_vector avoid;
+
+		avoid.start = (u64)ptr;
+		avoid.size = sizeof(*ptr) + ptr->len;
+
+		if (mem_overlaps(img, &avoid))
+			return true;
+
+		ptr = (struct setup_data *)(unsigned long)ptr->next;
+	}
+
 	return false;
 }

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