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>

diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c
index fc6091abedb7ff363da950a0766f45f9834cf1df..d39189ba7f8e5f03397599814ae22f7f79d7a03a 100644 (file)
--- 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;
 }