1 files changed, 75 insertions, 0 deletions
diff --git a/debian/patches/0065-loader-efi-chainloader-Use-grub_loader_set_ex.patch b/debian/patches/0065-loader-efi-chainloader-Use-grub_loader_set_ex.patch
new file mode 100644
index 0000000..4a4a0e7
--- /dev/null
+++ b/debian/patches/0065-loader-efi-chainloader-Use-grub_loader_set_ex.patch
@@ -0,0 +1,75 @@
+From 19b4f19cfea30655032c978e228d78e056f55f1a Mon Sep 17 00:00:00 2001
+From: Chris Coulson <chris.coulson@canonical.com>
+Date: Tue, 5 Apr 2022 11:48:58 +0100
+Subject: loader/efi/chainloader: Use grub_loader_set_ex()
+
+This ports the EFI chainloader to use grub_loader_set_ex() in order to fix
+a use-after-free bug that occurs when grub_cmd_chainloader() is executed
+more than once before a boot attempt is performed.
+
+Fixes: CVE-2022-28736
+
+Signed-off-by: Chris Coulson <chris.coulson@canonical.com>
+Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
+---
+ grub-core/loader/efi/chainloader.c | 16 +++++++---------
+ 1 file changed, 7 insertions(+), 9 deletions(-)
+
+diff --git a/grub-core/loader/efi/chainloader.c b/grub-core/loader/efi/chainloader.c
+index d1602c89b..7557eb269 100644
+--- a/grub-core/loader/efi/chainloader.c
++++ b/grub-core/loader/efi/chainloader.c
+@@ -44,11 +44,10 @@ GRUB_MOD_LICENSE ("GPLv3+");
+ 
+ static grub_dl_t my_mod;
+ 
+-static grub_efi_handle_t image_handle;
+-
+ static grub_err_t
+-grub_chainloader_unload (void)
++grub_chainloader_unload (void *context)
+ {
++  grub_efi_handle_t image_handle = (grub_efi_handle_t) context;
+   grub_efi_loaded_image_t *loaded_image;
+   grub_efi_boot_services_t *b;
+ 
+@@ -64,8 +63,9 @@ grub_chainloader_unload (void)
+ }
+ 
+ static grub_err_t
+-grub_chainloader_boot (void)
++grub_chainloader_boot (void *context)
+ {
++  grub_efi_handle_t image_handle = (grub_efi_handle_t) context;
+   grub_efi_boot_services_t *b;
+   grub_efi_status_t status;
+   grub_efi_uintn_t exit_data_size;
+@@ -225,6 +225,7 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
+   grub_efi_physical_address_t address = 0;
+   grub_efi_uintn_t pages = 0;
+   grub_efi_char16_t *cmdline = NULL;
++  grub_efi_handle_t image_handle = NULL;
+ 
+   if (argc == 0)
+     return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
+@@ -405,7 +406,7 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
+   efi_call_2 (b->free_pages, address, pages);
+   grub_free (file_path);
+ 
+-  grub_loader_set (grub_chainloader_boot, grub_chainloader_unload, 0);
++  grub_loader_set_ex (grub_chainloader_boot, grub_chainloader_unload, image_handle, 0);
+   return 0;
+ 
+  fail:
+@@ -423,10 +424,7 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
+     efi_call_2 (b->free_pages, address, pages);
+ 
+   if (image_handle != NULL)
+-    {
+-      efi_call_1 (b->unload_image, image_handle);
+-      image_handle = NULL;
+-    }
++    efi_call_1 (b->unload_image, image_handle);
+ 
+   grub_dl_unref (my_mod);
+