From: Andrei Borzenkov <arvidjaar@gmail.com>
To: grub-devel@gnu.org
Subject: [PATCH] mkimage: zero fill alignment space
Date: Fri, 30 Oct 2015 18:49:58 +0300
Message-Id: <1446220198-29899-1-git-send-email-arvidjaar@gmail.com>
Precedence: list
Reply-To: The development of GNU GRUB <grub-devel@gnu.org>

This did not cause real problem but is good for reproducible builds. I hit
it with recent bootinfoscript that displays embedded config; I was puzzled
by random garbage at the end.

Also remove redundant zeroing code where we fill in the whole memory block
anyway.

---
 util/mkimage.c | 29 +++++++++++++----------------
 1 file changed, 13 insertions(+), 16 deletions(-)

diff --git a/util/mkimage.c b/util/mkimage.c
index 35df998..1c522fe 100644
--- a/util/mkimage.c
+++ b/util/mkimage.c
@@ -992,7 +992,7 @@ grub_install_generate_image (const char *dir, const char *prefix,
 {
   char *kernel_img, *core_img;
   size_t kernel_size, total_module_size, core_size, exec_size;
-  size_t memdisk_size = 0, config_size = 0, config_size_pure = 0;
+  size_t memdisk_size = 0, memdisk_size_pure = 0, config_size = 0, config_size_pure = 0;
   size_t prefix_size = 0;
   char *kernel_path;
   size_t offset;
@@ -1035,7 +1035,8 @@ grub_install_generate_image (const char *dir, const char *prefix,
 
   if (memdisk_path)
     {
-      memdisk_size = ALIGN_UP(grub_util_get_image_size (memdisk_path), 512);
+      memdisk_size_pure = grub_util_get_image_size (memdisk_path);
+      memdisk_size = ALIGN_UP(memdisk_size_pure, 512);
       grub_util_info ("the size of memory disk is 0x%" GRUB_HOST_PRIxLONG_LONG,
 		      (unsigned long long) memdisk_size);
       total_module_size += memdisk_size + sizeof (struct grub_module_header);
@@ -1043,8 +1044,8 @@ grub_install_generate_image (const char *dir, const char *prefix,
 
   if (config_path)
     {
-      config_size_pure = grub_util_get_image_size (config_path) + 1;
-      config_size = ALIGN_ADDR (config_size_pure);
+      config_size_pure = grub_util_get_image_size (config_path);
+      config_size = ALIGN_ADDR (config_size_pure + 1);
       grub_util_info ("the size of config file is 0x%" GRUB_HOST_PRIxLONG_LONG,
 		      (unsigned long long) config_size);
       total_module_size += config_size + sizeof (struct grub_module_header);
@@ -1140,19 +1141,21 @@ grub_install_generate_image (const char *dir, const char *prefix,
     size_t i;
     for (i = 0; i < npubkeys; i++)
       {
-	size_t curs;
 	struct grub_module_header *header;
+	size_t key_size, orig_size;
 
-	curs = grub_util_get_image_size (pubkey_paths[i]);
+	orig_size = grub_util_get_image_size (pubkey_paths[i]);
+	key_size = ALIGN_ADDR (orig_size);
 
 	header = (struct grub_module_header *) (kernel_img + offset);
 	memset (header, 0, sizeof (struct grub_module_header));
 	header->type = grub_host_to_target32 (OBJ_TYPE_PUBKEY);
-	header->size = grub_host_to_target32 (curs + sizeof (*header));
+	header->size = grub_host_to_target32 (key_size + sizeof (*header));
 	offset += sizeof (*header);
 
 	grub_util_load_image (pubkey_paths[i], kernel_img + offset);
-	offset += ALIGN_ADDR (curs);
+	memset (kernel_img + offset + orig_size, 0, key_size - orig_size);
+	offset += key_size;
       }
   }
 
@@ -1167,6 +1170,7 @@ grub_install_generate_image (const char *dir, const char *prefix,
       offset += sizeof (*header);
 
       grub_util_load_image (memdisk_path, kernel_img + offset);
+      memset (kernel_img + offset + memdisk_size_pure, 0, memdisk_size - memdisk_size_pure);
       offset += memdisk_size;
     }
 
@@ -1181,7 +1185,7 @@ grub_install_generate_image (const char *dir, const char *prefix,
       offset += sizeof (*header);
 
       grub_util_load_image (config_path, kernel_img + offset);
-      *(kernel_img + offset + config_size_pure - 1) = 0;
+      memset (kernel_img + offset + config_size_pure, 0, config_size - config_size_pure);
       offset += config_size;
     }
 
@@ -1267,17 +1271,10 @@ grub_install_generate_image (const char *dir, const char *prefix,
 	      = grub_host_to_target_addr (image_target->link_addr);
 	}
       full_size = core_size + decompress_size;
-
       full_img = xmalloc (full_size);
-      memset (full_img, 0, full_size); 
-
       memcpy (full_img, decompress_img, decompress_size);
-
       memcpy (full_img + decompress_size, core_img, core_size);
 
-      memset (full_img + decompress_size + core_size, 0,
-	      full_size - (decompress_size + core_size));
-
       free (core_img);
       core_img = full_img;
       core_size = full_size;
-- 
tg: (2066766..) u/mkimage-zero-pad (depends on: master)