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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg59@coreos.com>
Date: Fri, 5 Jul 2019 21:12:00 +0200
Subject: [PATCH] Rework linux16 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 int it
before pulling out the individual blocks later on.
---
 grub-core/loader/i386/pc/linux.c | 33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/grub-core/loader/i386/pc/linux.c b/grub-core/loader/i386/pc/linux.c
index eea25ea39ca..73fb91e0570 100644
--- a/grub-core/loader/i386/pc/linux.c
+++ b/grub-core/loader/i386/pc/linux.c
@@ -123,13 +123,14 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
   grub_file_t file = 0;
   struct linux_i386_kernel_header lh;
   grub_uint8_t setup_sects;
-  grub_size_t real_size;
+  grub_size_t real_size, kernel_offset = 0;
   grub_ssize_t len;
   int i;
   char *grub_linux_prot_chunk;
   int grub_linux_is_bzimage;
   grub_addr_t grub_linux_prot_target;
   grub_err_t err;
+  grub_uint8_t *kernel = NULL;
 
   grub_dl_ref (my_mod);
 
@@ -143,7 +144,15 @@ 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"),
@@ -151,6 +160,9 @@ 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");
@@ -314,13 +326,9 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
   grub_memmove (grub_linux_real_chunk, &lh, sizeof (lh));
 
   len = real_size + GRUB_DISK_SECTOR_SIZE - sizeof (lh);
-  if (grub_file_read (file, grub_linux_real_chunk + sizeof (lh), len) != len)
-    {
-      if (!grub_errno)
-	grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
-		    argv[0]);
-      goto fail;
-    }
+  grub_memcpy (grub_linux_real_chunk + sizeof (lh), kernel + kernel_offset,
+	       len);
+  kernel_offset += len;
 
   if (lh.header != grub_cpu_to_le32_compile_time (GRUB_LINUX_I386_MAGIC_SIGNATURE)
       || grub_le_to_cpu16 (lh.version) < 0x0200)
@@ -358,9 +366,8 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
   }
 
   len = grub_linux16_prot_size;
-  if (grub_file_read (file, grub_linux_prot_chunk, len) != len && !grub_errno)
-    grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
-		argv[0]);
+  grub_memcpy (grub_linux_prot_chunk, kernel + kernel_offset, len);
+  kernel_offset += len;
 
   if (grub_errno == GRUB_ERR_NONE)
     {
@@ -370,6 +377,8 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
 
  fail:
 
+  grub_free (kernel);
+
   if (file)
     grub_file_close (file);