[tip:x86/urgent] x86/kaslr: Avoid the setup_data area when picking location

tip-bot for Kees Cook
2014-09-19T11:49:38Z

Commit-ID: 0cacbfbeb5077b63d5d3cf6df88b14ac12ad584b
Gitweb: http://git.kernel.org/tip/0cacbfbeb5077b63d5d3cf6df88b14ac12ad584b
Author: Kees Cook <keescook@chromium.org>
AuthorDate: Thu, 11 Sep 2014 09:19:31 -0700
Committer: Ingo Molnar <mingo@kernel.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@chromium.org>
Tested-by: Baoquan He <bhe@redhat.com>
Cc: stable@vger.kernel.org
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140911161931.GA12001@www.outflux.net
Signed-off-by: Ingo Molnar <mingo@kernel.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;
}