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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Matthew Garrett <mjg59@coreos.com>
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Date: Tue, 14 Jul 2015 16:58:51 -0700
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Subject: [PATCH] Fix race in EFI validation
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---
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 grub-core/loader/i386/efi/linux.c | 44 ++++++++++-----------------------------
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 1 file changed, 11 insertions(+), 33 deletions(-)
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diff --git a/grub-core/loader/i386/efi/linux.c b/grub-core/loader/i386/efi/linux.c
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index e5b778577f9..7ccf32d9d45 100644
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--- a/grub-core/loader/i386/efi/linux.c
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+++ b/grub-core/loader/i386/efi/linux.c
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@@ -154,7 +154,7 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
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   grub_file_t file = 0;
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   struct linux_kernel_header lh;
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   grub_ssize_t len, start, filelen;
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-  void *kernel;
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+  void *kernel = NULL;
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   grub_dl_ref (my_mod);
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@@ -191,10 +191,6 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
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       goto fail;
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     }
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-  grub_file_seek (file, 0);
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-
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-  grub_free(kernel);
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-
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   params = grub_efi_allocate_pages_max (0x3fffffff, BYTES_TO_PAGES(16384));
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   if (! params)
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@@ -203,15 +199,9 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
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       goto fail;
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     }
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-  memset (params, 0, 16384);
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+  grub_memset (params, 0, 16384);
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-  if (grub_file_read (file, &lh, sizeof (lh)) != sizeof (lh))
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-    {
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-      if (!grub_errno)
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-	grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
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-		    argv[0]);
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-      goto fail;
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-    }
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+  grub_memcpy (&lh, kernel, sizeof (lh));
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   if (lh.boot_flag != grub_cpu_to_le16 (0xaa55))
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     {
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@@ -271,27 +261,12 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
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       goto fail;
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     }
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-  if (grub_file_seek (file, start) == (grub_off_t) -1)
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-    {
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-      grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
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-		  argv[0]);
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-      goto fail;
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-    }
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+  grub_memcpy (kernel_mem, (char *)kernel + start, len);
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+  grub_loader_set (grub_linuxefi_boot, grub_linuxefi_unload, 0);
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+  loaded=1;
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-  if (grub_file_read (file, kernel_mem, len) != len && !grub_errno)
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-    {
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-      grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
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-		  argv[0]);
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-    }
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-
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-  if (grub_errno == GRUB_ERR_NONE)
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-    {
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-      grub_loader_set (grub_linuxefi_boot, grub_linuxefi_unload, 0);
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-      loaded = 1;
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-      lh.code32_start = (grub_uint32_t)(grub_uint64_t) kernel_mem;
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-    }
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-
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-  memcpy(params, &lh, 2 * 512);
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+  lh.code32_start = (grub_uint32_t)(grub_uint64_t) kernel_mem;
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+  grub_memcpy (params, &lh, 2 * 512);
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   params->type_of_loader = 0x21;
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@@ -300,6 +275,9 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
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   if (file)
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     grub_file_close (file);
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+  if (kernel)
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+    grub_free (kernel);
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+
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   if (grub_errno != GRUB_ERR_NONE)
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     {
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       grub_dl_unref (my_mod);