mkimage: zero fill alignment space

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.

Prezero memory buffer used to assemble core.img. This makes individual
memset redundant. Also ensure buffer is filled with zeroes in several other
places.

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

util/grub-mkimagexx.c

@@ -101,7 +101,7 @@ SUFFIX (generate_elf) (const struct grub_install_image_target_desc *image_target
   program_size = ALIGN_ADDR (*core_size);
 
   elf_img = xmalloc (program_size + header_size + footer_size);
-  memset (elf_img, 0, program_size + header_size);
+  memset (elf_img, 0, program_size + header_size + footer_size);
   memcpy (elf_img  + header_size, *core_img, *core_size);
   ehdr = (void *) elf_img;
   phdr = (void *) (elf_img + sizeof (*ehdr));
@@ -1587,6 +1587,7 @@ SUFFIX (load_image) (const char *kernel_path, size_t *exec_size,
     }
 
   out_img = xmalloc (*kernel_sz + total_module_size);
+  memset (out_img, 0, *kernel_sz + total_module_size);
 
   if (image_target->id == IMAGE_EFI)
     {

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, config_size = 0;
   size_t prefix_size = 0;
   char *kernel_path;
   size_t offset;
@@ -1043,8 +1043,7 @@ 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 (grub_util_get_image_size (config_path) + 1);
-      config_size = ALIGN_ADDR (config_size_pure);
       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);
@@ -1080,7 +1079,10 @@ grub_install_generate_image (const char *dir, const char *prefix,
       = grub_host_to_target32 (total_module_size);
 
   if (image_target->flags & PLATFORM_FLAGS_MODULES_BEFORE_KERNEL)
+    {
       memmove (kernel_img + total_module_size, kernel_img, kernel_size);
+      memset (kernel_img, 0, total_module_size);
+    }
 
   if (image_target->voidp_sizeof == 8)
     {
@@ -1090,7 +1092,6 @@ grub_install_generate_image (const char *dir, const char *prefix,
 	modinfo = (struct grub_module_info64 *) kernel_img;
       else
 	modinfo = (struct grub_module_info64 *) (kernel_img + kernel_size);
-      memset (modinfo, 0, sizeof (struct grub_module_info64));
       modinfo->magic = grub_host_to_target32 (GRUB_MODULE_MAGIC);
       modinfo->offset = grub_host_to_target_addr (sizeof (struct grub_module_info64));
       modinfo->size = grub_host_to_target_addr (total_module_size);
@@ -1107,7 +1108,6 @@ grub_install_generate_image (const char *dir, const char *prefix,
 	modinfo = (struct grub_module_info32 *) kernel_img;
       else
 	modinfo = (struct grub_module_info32 *) (kernel_img + kernel_size);
-      memset (modinfo, 0, sizeof (struct grub_module_info32));
       modinfo->magic = grub_host_to_target32 (GRUB_MODULE_MAGIC);
       modinfo->offset = grub_host_to_target_addr (sizeof (struct grub_module_info32));
       modinfo->size = grub_host_to_target_addr (total_module_size);
@@ -1120,17 +1120,14 @@ grub_install_generate_image (const char *dir, const char *prefix,
   for (p = path_list; p; p = p->next)
     {
       struct grub_module_header *header;
-      size_t mod_size, orig_size;
+      size_t mod_size;
 
-      orig_size = grub_util_get_image_size (p->name);
+      mod_size = ALIGN_ADDR (grub_util_get_image_size (p->name));
-      mod_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_ELF);
       header->size = grub_host_to_target32 (mod_size + sizeof (*header));
       offset += sizeof (*header);
-      memset (kernel_img + offset + orig_size, 0, mod_size - orig_size);
 
       grub_util_load_image (p->name, kernel_img + offset);
       offset += mod_size;
@@ -1146,7 +1143,6 @@ grub_install_generate_image (const char *dir, const char *prefix,
 	curs = grub_util_get_image_size (pubkey_paths[i]);
 
 	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));
 	offset += sizeof (*header);
@@ -1161,7 +1157,6 @@ grub_install_generate_image (const char *dir, const char *prefix,
       struct grub_module_header *header;
 
       header = (struct grub_module_header *) (kernel_img + offset);
-      memset (header, 0, sizeof (struct grub_module_header));
       header->type = grub_host_to_target32 (OBJ_TYPE_MEMDISK);
       header->size = grub_host_to_target32 (memdisk_size + sizeof (*header));
       offset += sizeof (*header);
@@ -1175,13 +1170,11 @@ grub_install_generate_image (const char *dir, const char *prefix,
       struct grub_module_header *header;
 
       header = (struct grub_module_header *) (kernel_img + offset);
-      memset (header, 0, sizeof (struct grub_module_header));
       header->type = grub_host_to_target32 (OBJ_TYPE_CONFIG);
       header->size = grub_host_to_target32 (config_size + sizeof (*header));
       offset += sizeof (*header);
 
       grub_util_load_image (config_path, kernel_img + offset);
-      *(kernel_img + offset + config_size_pure - 1) = 0;
       offset += config_size;
     }
 
@@ -1190,12 +1183,10 @@ grub_install_generate_image (const char *dir, const char *prefix,
       struct grub_module_header *header;
 
       header = (struct grub_module_header *) (kernel_img + offset);
-      memset (header, 0, sizeof (struct grub_module_header));
       header->type = grub_host_to_target32 (OBJ_TYPE_PREFIX);
       header->size = grub_host_to_target32 (prefix_size + sizeof (*header));
       offset += sizeof (*header);
 
-      grub_memset (kernel_img + offset, 0, prefix_size);
       grub_strcpy (kernel_img + offset, prefix);
       offset += prefix_size;
     }
@@ -1269,15 +1260,11 @@ grub_install_generate_image (const char *dir, const char *prefix,
       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;
@@ -1428,6 +1415,7 @@ grub_install_generate_image (const char *dir, const char *prefix,
 	pe_img = xmalloc (reloc_addr + reloc_size);
 	memset (pe_img, 0, header_size);
 	memcpy ((char *) pe_img + header_size, core_img, core_size);
+	memset ((char *) pe_img + header_size + core_size, 0, reloc_addr - (header_size + core_size));
 	memcpy ((char *) pe_img + reloc_addr, rel_section, reloc_size);
 	header = pe_img;