x86, boot: Sanitize boot_params if not zeroed on creation

Use the new sentinel field to detect bootloaders which fail to follow
protocol and don't initialize fields in struct boot_params that they
do not explicitly initialize to zero.

Based on an original patch and research by Yinghai Lu.
Changed by hpa to be invoked both in the decompression path and in the
kernel proper; the latter for the case where a bootloader takes over
decompression.

Originally-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1359058816-7615-26-git-send-email-yinghai@kernel.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

2 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index 88f7ff6da404..7cb56c6ca351 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -325,6 +325,8 @@ asmlinkage void decompress_kernel(void *rmode, memptr heap,
 {
         real_mode = rmode;
 
+        sanitize_boot_params(real_mode);
+
         if (real_mode->screen_info.orig_video_mode == 7) {
                 vidmem = (char *) 0xb0000;
                 vidport = 0x3b4;
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index 0e6dc0ee0eea..674019d8e235 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -18,6 +18,7 @@
 #include <asm/page.h>
 #include <asm/boot.h>
 #include <asm/bootparam.h>
+#include <asm/bootparam_utils.h>
 
 #define BOOT_BOOT_H
 #include "../ctype.h"