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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg59@coreos.com>
Date: Fri, 5 Jul 2019 20:54:51 +0200
Subject: [PATCH] Rework linux command

We want a single buffer that contains the entire kernel image in order to
perform a TPM measurement. Allocate one and copy the entire kernel into it
before pulling out the individual blocks later on.
---
 grub-core/loader/i386/linux.c | 36 +++++++++++++++++++++++-------------
 1 file changed, 23 insertions(+), 13 deletions(-)

diff --git a/grub-core/loader/i386/linux.c b/grub-core/loader/i386/linux.c
index d0501e22957..b255c950526 100644
--- a/grub-core/loader/i386/linux.c
+++ b/grub-core/loader/i386/linux.c
@@ -641,13 +641,15 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
 {
   grub_file_t file = 0;
   struct linux_i386_kernel_header lh;
+  grub_uint8_t *linux_params_ptr;
   grub_uint8_t setup_sects;
-  grub_size_t real_size, prot_size, prot_file_size;
+  grub_size_t real_size, prot_size, prot_file_size, kernel_offset;
   grub_ssize_t len;
   int i;
   grub_size_t align, min_align;
   int relocatable;
   grub_uint64_t preferred_address = GRUB_LINUX_BZIMAGE_ADDR;
+  grub_uint8_t *kernel = NULL;
 
   grub_dl_ref (my_mod);
 
@@ -661,7 +663,15 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
   if (! file)
     goto fail;
 
-  if (grub_file_read (file, &lh, sizeof (lh)) != sizeof (lh))
+  len = grub_file_size (file);
+  kernel = grub_malloc (len);
+  if (!kernel)
+    {
+      grub_error (GRUB_ERR_OUT_OF_MEMORY, N_("cannot allocate kernel buffer"));
+      goto fail;
+    }
+
+  if (grub_file_read (file, kernel, len) != len)
     {
       if (!grub_errno)
 	grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
@@ -669,6 +679,9 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
       goto fail;
     }
 
+  grub_memcpy (&lh, kernel, sizeof (lh));
+  kernel_offset = sizeof (lh);
+
   if (lh.boot_flag != grub_cpu_to_le16_compile_time (0xaa55))
     {
       grub_error (GRUB_ERR_BAD_OS, "invalid magic number");
@@ -760,6 +773,7 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
 		      preferred_address))
     goto fail;
 
+
   grub_memset (&linux_params, 0, sizeof (linux_params));
   grub_memcpy (&linux_params.setup_sects, &lh.setup_sects, sizeof (lh) - 0x1F1);
 
@@ -782,13 +796,9 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
   /* We've already read lh so there is no need to read it second time. */
   len -= sizeof(lh);
 
-  if (grub_file_read (file, (char *) &linux_params + sizeof (lh), len) != len)
-    {
-      if (!grub_errno)
-	grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
-		    argv[0]);
-      goto fail;
-    }
+  linux_params_ptr = (void *)&linux_params;
+  grub_memcpy (linux_params_ptr + sizeof (lh), kernel + kernel_offset, len);
+  kernel_offset += len;
 
   linux_params.type_of_loader = GRUB_LINUX_BOOT_LOADER_TYPE;
 
@@ -847,7 +857,7 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
 
   /* The other parameters are filled when booting.  */
 
-  grub_file_seek (file, real_size + GRUB_DISK_SECTOR_SIZE);
+  kernel_offset = real_size + GRUB_DISK_SECTOR_SIZE;
 
   grub_dprintf ("linux", "bzImage, setup=0x%x, size=0x%x\n",
 		(unsigned) real_size, (unsigned) prot_size);
@@ -1001,9 +1011,7 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
   }
 
   len = prot_file_size;
-  if (grub_file_read (file, prot_mode_mem, len) != len && !grub_errno)
-    grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
-		argv[0]);
+  grub_memcpy (prot_mode_mem, kernel + kernel_offset, len);
 
   if (grub_errno == GRUB_ERR_NONE)
     {
@@ -1014,6 +1022,8 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
 
  fail:
 
+  grub_free (kernel);
+
   if (file)
     grub_file_close (file);