[PATCH] x86, kaslr: avoid setup_data when picking location

Kees Cook
2014-09-11T16:20:08Z

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
---
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 fc6091abedb7..d39189ba7f8e 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;
}

--
1.9.1

--
Kees Cook
Chrome OS Security