buildroot/boot/grub2/0003-loader-efi-chainloader-Simplify-the-loader-state.patch

From dfdc742bdb22be468035f96cce0be5fee23b6df5 Mon Sep 17 00:00:00 2001
From: Chris Coulson <chris.coulson@canonical.com>
Date: Tue, 5 Apr 2022 10:02:04 +0100
Subject: [PATCH] loader/efi/chainloader: Simplify the loader state

The chainloader command retains the source buffer and device path passed
to LoadImage(), requiring the unload hook passed to grub_loader_set() to
free them. It isn't required to retain this state though - they aren't
required by StartImage() or anything else in the boot hook, so clean them
up before grub_cmd_chainloader() finishes.

Signed-off-by: Chris Coulson <chris.coulson@canonical.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Upstream: 1469983ebb9674753ad333d37087fb8cb20e1dce
[Thomas: needed to cherry-pick
04c86e0bb7b58fc2f913f798cdb18934933e532d which fixes CVE-2022-28736]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
---
 grub-core/loader/efi/chainloader.c | 38 +++++++++++++++++-------------
 1 file changed, 21 insertions(+), 17 deletions(-)

diff --git a/grub-core/loader/efi/chainloader.c b/grub-core/loader/efi/chainloader.c
index 2bd80f4db..d1602c89b 100644
--- a/grub-core/loader/efi/chainloader.c
+++ b/grub-core/loader/efi/chainloader.c
@@ -44,25 +44,20 @@ GRUB_MOD_LICENSE ("GPLv3+");
 
 static grub_dl_t my_mod;
 
-static grub_efi_physical_address_t address;
-static grub_efi_uintn_t pages;
-static grub_efi_device_path_t *file_path;
 static grub_efi_handle_t image_handle;
-static grub_efi_char16_t *cmdline;
 
 static grub_err_t
 grub_chainloader_unload (void)
 {
+  grub_efi_loaded_image_t *loaded_image;
   grub_efi_boot_services_t *b;
 
+  loaded_image = grub_efi_get_loaded_image (image_handle);
+  if (loaded_image != NULL)
+    grub_free (loaded_image->load_options);
+
   b = grub_efi_system_table->boot_services;
   efi_call_1 (b->unload_image, image_handle);
-  efi_call_2 (b->free_pages, address, pages);
-
-  grub_free (file_path);
-  grub_free (cmdline);
-  cmdline = 0;
-  file_path = 0;
 
   grub_dl_unref (my_mod);
   return GRUB_ERR_NONE;
@@ -140,7 +135,7 @@ make_file_path (grub_efi_device_path_t *dp, const char *filename)
   char *dir_start;
   char *dir_end;
   grub_size_t size;
-  grub_efi_device_path_t *d;
+  grub_efi_device_path_t *d, *file_path;
 
   dir_start = grub_strchr (filename, ')');
   if (! dir_start)
@@ -222,11 +217,14 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
   grub_efi_status_t status;
   grub_efi_boot_services_t *b;
   grub_device_t dev = 0;
-  grub_efi_device_path_t *dp = 0;
+  grub_efi_device_path_t *dp = NULL, *file_path = NULL;
   grub_efi_loaded_image_t *loaded_image;
   char *filename;
   void *boot_image = 0;
   grub_efi_handle_t dev_handle = 0;
+  grub_efi_physical_address_t address = 0;
+  grub_efi_uintn_t pages = 0;
+  grub_efi_char16_t *cmdline = NULL;
 
   if (argc == 0)
     return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
@@ -234,11 +232,6 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
 
   grub_dl_ref (my_mod);
 
-  /* Initialize some global variables.  */
-  address = 0;
-  image_handle = 0;
-  file_path = 0;
-
   b = grub_efi_system_table->boot_services;
 
   file = grub_file_open (filename, GRUB_FILE_TYPE_EFI_CHAINLOADED_IMAGE);
@@ -408,6 +401,10 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
   grub_file_close (file);
   grub_device_close (dev);
 
+  /* We're finished with the source image buffer and file path now. */
+  efi_call_2 (b->free_pages, address, pages);
+  grub_free (file_path);
+
   grub_loader_set (grub_chainloader_boot, grub_chainloader_unload, 0);
   return 0;
 
@@ -419,11 +416,18 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
   if (file)
     grub_file_close (file);
 
+  grub_free (cmdline);
   grub_free (file_path);
 
   if (address)
     efi_call_2 (b->free_pages, address, pages);
 
+  if (image_handle != NULL)
+    {
+      efi_call_1 (b->unload_image, image_handle);
+      image_handle = NULL;
+    }
+
   grub_dl_unref (my_mod);
 
   return grub_errno;
-- 
2.41.0