linux-kernel - [tip:x86/urgent] x86/kaslr: Avoid the setup

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Message-ID: <tip-0cacbfbeb5077b63d5d3cf6df88b14ac12ad584b@git.kernel.org>
Date:	Fri, 19 Sep 2014 04:49:07 -0700
From:	tip-bot for Kees Cook <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	torvalds@...ux-foundation.org, bhe@...hat.com,
	rafael.j.wysocki@...el.com, vgoyal@...hat.com, pavel@....cz,
	keescook@...omium.org, yongjun_wei@...ndmicro.com.cn,
	tglx@...utronix.de
Subject: [tip:x86/urgent] x86/kaslr:
  Avoid the setup_data area when picking location

Commit-ID:  0cacbfbeb5077b63d5d3cf6df88b14ac12ad584b
Gitweb:     http://git.kernel.org/tip/0cacbfbeb5077b63d5d3cf6df88b14ac12ad584b
Author:     Kees Cook <keescook@...omium.org>
AuthorDate: Thu, 11 Sep 2014 09:19:31 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 19 Sep 2014 13:04:29 +0200

x86/kaslr: Avoid the setup_data area when picking location

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: stable@...r.kernel.org
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>
---
 arch/x86/boot/compressed/aslr.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c
index fc6091a..d39189b 100644
--- 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 input, unsigned long input_size,
 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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