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loader/efi/chainloader: Use grub_loader_set_ex()

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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>
This commit is contained in:
Chris Coulson 2022-04-05 11:48:58 +01:00 committed by Julian Andres Klode
parent bb35dbb9bf
commit 19b4f19cfe
1 changed files with 7 additions and 9 deletions
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16
grub-core/loader/efi/chainloader.c
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@ -44,11 +44,10 @@ GRUB_MOD_LICENSE ("GPLv3+");
static grub_dl_t my_mod; static grub_dl_t my_mod;
static grub_efi_handle_t image_handle;
static grub_err_t 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_loaded_image_t *loaded_image;
grub_efi_boot_services_t *b; grub_efi_boot_services_t *b;
@ -64,8 +63,9 @@ grub_chainloader_unload (void)
} }
static grub_err_t 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_boot_services_t *b;
grub_efi_status_t status; grub_efi_status_t status;
grub_efi_uintn_t exit_data_size; 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_physical_address_t address = 0;
grub_efi_uintn_t pages = 0; grub_efi_uintn_t pages = 0;
grub_efi_char16_t *cmdline = NULL; grub_efi_char16_t *cmdline = NULL;
grub_efi_handle_t image_handle = NULL;
if (argc == 0) if (argc == 0)
return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected")); 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); efi_call_2 (b->free_pages, address, pages);
grub_free (file_path); 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; return 0;
fail: fail:
@ -423,10 +424,7 @@ grub_cmd_chainloader (grub_command_t cmd __attribute__ ((unused)),
efi_call_2 (b->free_pages, address, pages); efi_call_2 (b->free_pages, address, pages);
if (image_handle != NULL) if (image_handle != NULL)
{ efi_call_1 (b->unload_image, image_handle);
efi_call_1 (b->unload_image, image_handle);
image_handle = NULL;
}
grub_dl_unref (my_mod); grub_dl_unref (my_mod);