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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Chris Coulson <chris.coulson@canonical.com>
Date: Fri, 29 Apr 2022 21:30:56 +0100
Subject: [PATCH] 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.
Signed-off-by: Chris Coulson <chris.coulson@canonical.com>
(cherry picked from commit 4b7f0402b7cb0f67a93be736f2b75b818d7f44c9)
(cherry picked from commit fc1a79bf0e0bc019362ace46d908a92b48dcd55b)
[rharwood: context sludge from previous commit]
Signed-off-by: Robbie Harwood <rharwood@redhat.com>
---
grub-core/loader/efi/chainloader.c | 38 ++++++++++++++++++++++----------------
1 file changed, 22 insertions(+), 16 deletions(-)
diff --git a/grub-core/loader/efi/chainloader.c b/grub-core/loader/efi/chainloader.c
index 0717ce0478..8ef508beca 100644
--- a/grub-core/loader/efi/chainloader.c
+++ b/grub-core/loader/efi/chainloader.c
@@ -48,8 +48,6 @@ GRUB_MOD_LICENSE ("GPLv3+");
static grub_dl_t my_mod;
-static grub_efi_handle_t image_handle;
-
struct grub_secureboot_chainloader_context {
grub_efi_physical_address_t address;
grub_efi_uintn_t pages;
@@ -59,7 +57,6 @@ struct grub_secureboot_chainloader_context {
grub_ssize_t cmdline_len;
grub_efi_handle_t dev_handle;
};
-static struct grub_secureboot_chainloader_context *sb_context;
static grub_err_t
grub_start_image (grub_efi_handle_t handle)
@@ -98,11 +95,14 @@ grub_start_image (grub_efi_handle_t handle)
}
static grub_err_t
-grub_chainloader_unload (void)
+grub_chainloader_unload (void *context)
{
+ grub_efi_handle_t image_handle;
grub_efi_loaded_image_t *loaded_image;
grub_efi_boot_services_t *b;
+ image_handle = (grub_efi_handle_t) context;
+
loaded_image = grub_efi_get_loaded_image (image_handle);
if (loaded_image != NULL)
grub_free (loaded_image->load_options);
@@ -115,10 +115,12 @@ grub_chainloader_unload (void)
}
static grub_err_t
-grub_chainloader_boot (void)
+grub_chainloader_boot (void *context)
{
+ grub_efi_handle_t image_handle;
grub_err_t err;
+ image_handle = (grub_efi_handle_t) context;
err = grub_start_image (image_handle);
grub_loader_unset ();
@@ -839,15 +841,17 @@ error_exit:
}
static grub_err_t
-grub_secureboot_chainloader_unload (void)
+grub_secureboot_chainloader_unload (void *context)
{
+ struct grub_secureboot_chainloader_context *sb_context;
+
+ sb_context = (struct grub_secureboot_chainloader_context *) context;
+
grub_efi_free_pages (sb_context->address, sb_context->pages);
grub_free (sb_context->file_path);
grub_free (sb_context->cmdline);
grub_free (sb_context);
- sb_context = 0;
-
grub_dl_unref (my_mod);
return GRUB_ERR_NONE;
}
@@ -896,12 +900,15 @@ grub_load_image(grub_efi_device_path_t *file_path, void *boot_image,
}
static grub_err_t
-grub_secureboot_chainloader_boot (void)
+grub_secureboot_chainloader_boot (void *context)
{
+ struct grub_secureboot_chainloader_context *sb_context;
grub_efi_boot_services_t *b;
int rc;
grub_efi_handle_t handle = 0;
+ sb_context = (struct grub_secureboot_chainloader_context *) context;
+
rc = handle_image (sb_context);
if (rc == 0)
{
@@ -943,6 +950,8 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
grub_efi_char16_t *cmdline = 0;
grub_ssize_t cmdline_len = 0;
grub_efi_handle_t dev_handle = 0;
+ grub_efi_handle_t image_handle = 0;
+ struct grub_secureboot_chainloader_context *sb_context = 0;
if (argc == 0)
return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
@@ -1130,8 +1139,8 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
grub_file_close (file);
grub_device_close (dev);
- grub_loader_set (grub_secureboot_chainloader_boot,
- grub_secureboot_chainloader_unload, 0);
+ grub_loader_set_ex (grub_secureboot_chainloader_boot,
+ grub_secureboot_chainloader_unload, sb_context, 0);
return 0;
}
else if (rc == 0)
@@ -1145,7 +1154,7 @@ 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;
}
@@ -1173,10 +1182,7 @@ fail:
grub_free (cmdline);
if (image_handle != 0)
- {
- efi_call_1 (b->unload_image, image_handle);
- image_handle = 0;
- }
+ efi_call_1 (b->unload_image, image_handle);
grub_dl_unref (my_mod);