From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Chris Coulson <chris.coulson@canonical.com>
Date: Mon, 2 May 2022 17:04:23 +0200
Subject: [PATCH] loader/i386/efi/linux: Use grub_loader_set_ex
This ports the linuxefi loader to use grub_loader_set_ex in order to fix
a use-after-fre bug that occurs when grub_cmd_linux is executed more than
once before a boot attempt is performed.
This is more complicated than for the chainloader command, as the initrd
command needs access to the loader state. To solve this, the linuxefi
module registers a dummy initrd command at startup that returns an error.
The linuxefi command then registers a proper initrd command with a higher
priority that is passed the loader state.
Signed-off-by: Chris Coulson <chris.coulson@canonical.com>
(cherry picked from commit 7cf736436b4c934df5ddfa6f44b46a7e07d99fdc)
[rharwood/pjones: set kernel_size in context]
(cherry picked from commit 9c056391f7a36ea480de9a759c12e55a90f2040a)
[rharwood: verifying twice]
Signed-off-by: Robbie Harwood <rharwood@redhat.com>
---
grub-core/loader/i386/efi/linux.c | 146 +++++++++++++++++++++++---------------
1 file changed, 87 insertions(+), 59 deletions(-)
diff --git a/grub-core/loader/i386/efi/linux.c b/grub-core/loader/i386/efi/linux.c
index 08c9fe6b0e..9e25e51ccf 100644
--- a/grub-core/loader/i386/efi/linux.c
+++ b/grub-core/loader/i386/efi/linux.c
@@ -35,13 +35,19 @@
GRUB_MOD_LICENSE ("GPLv3+");
static grub_dl_t my_mod;
-static int loaded;
-static void *kernel_mem;
-static grub_uint64_t kernel_size;
-static void *initrd_mem;
-static grub_uint32_t handover_offset;
-struct linux_kernel_params *params;
-static char *linux_cmdline;
+
+static grub_command_t cmd_linux, cmd_initrd;
+static grub_command_t cmd_linuxefi, cmd_initrdefi;
+
+struct grub_linuxefi_context {
+ void *kernel_mem;
+ grub_uint64_t kernel_size;
+ grub_uint32_t handover_offset;
+ struct linux_kernel_params *params;
+ char *cmdline;
+
+ void *initrd_mem;
+};
#define MIN(a, b) \
({ typeof (a) _a = (a); \
@@ -124,25 +130,32 @@ kernel_alloc(grub_efi_uintn_t size, const char * const errmsg)
}
static grub_err_t
-grub_linuxefi_boot (void)
+grub_linuxefi_boot (void *data)
{
+ struct grub_linuxefi_context *context = (struct grub_linuxefi_context *) data;
+
asm volatile ("cli");
- return grub_efi_linux_boot ((char *)kernel_mem,
- handover_offset,
- params);
+ return grub_efi_linux_boot ((char *)context->kernel_mem,
+ context->handover_offset,
+ context->params);
}
static grub_err_t
-grub_linuxefi_unload (void)
+grub_linuxefi_unload (void *data)
{
+ struct grub_linuxefi_context *context = (struct grub_linuxefi_context *) data;
+ struct linux_kernel_params *params = context->params;
+
grub_dl_unref (my_mod);
- loaded = 0;
- kernel_free(initrd_mem, params->ramdisk_size);
- kernel_free(linux_cmdline, params->cmdline_size + 1);
- kernel_free(kernel_mem, kernel_size);
- kernel_free(params, sizeof(*params));
+ kernel_free (context->initrd_mem, params->ramdisk_size);
+ kernel_free (context->cmdline, params->cmdline_size + 1);
+ kernel_free (context->kernel_mem, context->kernel_size);
+ kernel_free (params, sizeof(*params));
+ cmd_initrd->data = 0;
+ cmd_initrdefi->data = 0;
+ grub_free (context);
return GRUB_ERR_NONE;
}
@@ -189,13 +202,14 @@ read(grub_file_t file, grub_uint8_t *bufp, grub_size_t len)
#define HIGH_U32(val) ((grub_uint32_t)(((grub_addr_t)(val) >> 32) & 0xffffffffull))
static grub_err_t
-grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
- int argc, char *argv[])
+grub_cmd_initrd (grub_command_t cmd, int argc, char *argv[])
{
grub_file_t *files = 0;
int i, nfiles = 0;
grub_size_t size = 0;
grub_uint8_t *ptr;
+ struct grub_linuxefi_context *context = (struct grub_linuxefi_context *) cmd->data;
+ struct linux_kernel_params *params;
if (argc == 0)
{
@@ -203,12 +217,14 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
goto fail;
}
- if (!loaded)
+ if (!context)
{
grub_error (GRUB_ERR_BAD_ARGUMENT, N_("you need to load the kernel first"));
goto fail;
}
+ params = context->params;
+
files = grub_calloc (argc, sizeof (files[0]));
if (!files)
goto fail;
@@ -226,19 +242,19 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
}
}
- initrd_mem = kernel_alloc(size, N_("can't allocate initrd"));
- if (initrd_mem == NULL)
+ context->initrd_mem = kernel_alloc(size, N_("can't allocate initrd"));
+ if (context->initrd_mem == NULL)
goto fail;
- grub_dprintf ("linux", "initrd_mem = %p\n", initrd_mem);
+ grub_dprintf ("linux", "initrd_mem = %p\n", context->initrd_mem);
params->ramdisk_size = LOW_U32(size);
- params->ramdisk_image = LOW_U32(initrd_mem);
+ params->ramdisk_image = LOW_U32(context->initrd_mem);
#if defined(__x86_64__)
params->ext_ramdisk_size = HIGH_U32(size);
- params->ext_ramdisk_image = HIGH_U32(initrd_mem);
+ params->ext_ramdisk_image = HIGH_U32(context->initrd_mem);
#endif
- ptr = initrd_mem;
+ ptr = context->initrd_mem;
for (i = 0; i < nfiles; i++)
{
@@ -262,8 +278,8 @@ grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
grub_file_close (files[i]);
grub_free (files);
- if (initrd_mem && grub_errno)
- grub_efi_free_pages ((grub_efi_physical_address_t)(grub_addr_t)initrd_mem,
+ if (context->initrd_mem && grub_errno)
+ grub_efi_free_pages ((grub_efi_physical_address_t)(grub_addr_t)context->initrd_mem,
BYTES_TO_PAGES(size));
return grub_errno;
@@ -279,6 +295,12 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
void *kernel = NULL;
int setup_header_end_offset;
int rc;
+ void *kernel_mem = 0;
+ grub_uint64_t kernel_size = 0;
+ grub_uint32_t handover_offset;
+ struct linux_kernel_params *params = 0;
+ char *cmdline = 0;
+ struct grub_linuxefi_context *context = 0;
grub_dl_ref (my_mod);
@@ -403,27 +425,27 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
grub_dprintf ("linux", "new lh is at %p\n", lh);
grub_dprintf ("linux", "setting up cmdline\n");
- linux_cmdline = kernel_alloc (lh->cmdline_size + 1, N_("can't allocate cmdline"));
- if (!linux_cmdline)
+ cmdline = kernel_alloc (lh->cmdline_size + 1, N_("can't allocate cmdline"));
+ if (!cmdline)
goto fail;
- grub_dprintf ("linux", "linux_cmdline = %p\n", linux_cmdline);
+ grub_dprintf ("linux", "cmdline = %p\n", cmdline);
- grub_memcpy (linux_cmdline, LINUX_IMAGE, sizeof (LINUX_IMAGE));
+ grub_memcpy (cmdline, LINUX_IMAGE, sizeof (LINUX_IMAGE));
grub_create_loader_cmdline (argc, argv,
- linux_cmdline + sizeof (LINUX_IMAGE) - 1,
+ cmdline + sizeof (LINUX_IMAGE) - 1,
lh->cmdline_size - (sizeof (LINUX_IMAGE) - 1),
GRUB_VERIFY_KERNEL_CMDLINE);
- grub_dprintf ("linux", "cmdline:%s\n", linux_cmdline);
+ grub_dprintf ("linux", "cmdline:%s\n", cmdline);
grub_dprintf ("linux", "setting lh->cmd_line_ptr to 0x%08x\n",
- LOW_U32(linux_cmdline));
- lh->cmd_line_ptr = LOW_U32(linux_cmdline);
+ LOW_U32(cmdline));
+ lh->cmd_line_ptr = LOW_U32(cmdline);
#if defined(__x86_64__)
- if ((grub_efi_uintn_t)linux_cmdline > 0xffffffffull)
+ if ((grub_efi_uintn_t)cmdline > 0xffffffffull)
{
grub_dprintf ("linux", "setting params->ext_cmd_line_ptr to 0x%08x\n",
- HIGH_U32(linux_cmdline));
- params->ext_cmd_line_ptr = HIGH_U32(linux_cmdline);
+ HIGH_U32(cmdline));
+ params->ext_cmd_line_ptr = HIGH_U32(cmdline);
}
#endif
@@ -448,16 +470,13 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
}
max_addresses[1].addr = GRUB_EFI_MAX_ALLOCATION_ADDRESS;
max_addresses[2].addr = GRUB_EFI_MAX_ALLOCATION_ADDRESS;
- kernel_mem = kernel_alloc (lh->init_size, N_("can't allocate kernel"));
+ kernel_size = lh->init_size;
+ kernel_mem = kernel_alloc (kernel_size, N_("can't allocate kernel"));
restore_addresses();
if (!kernel_mem)
goto fail;
grub_dprintf("linux", "kernel_mem = %p\n", kernel_mem);
- grub_loader_set (grub_linuxefi_boot, grub_linuxefi_unload, 0);
-
- loaded = 1;
-
grub_dprintf ("linux", "setting lh->code32_start to 0x%08x\n",
LOW_U32(kernel_mem));
lh->code32_start = LOW_U32(kernel_mem);
@@ -474,33 +493,42 @@ grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
"setting lh->ext_loader_{type,ver} = {0x%02x,0x%02x}\n",
params->ext_loader_type, params->ext_loader_ver);
+ context = grub_zalloc (sizeof (*context));
+ if (!context)
+ goto fail;
+ context->kernel_mem = kernel_mem;
+ context->kernel_size = kernel_size;
+ context->handover_offset = handover_offset;
+ context->params = params;
+ context->cmdline = cmdline;
+
+ grub_loader_set_ex (grub_linuxefi_boot, grub_linuxefi_unload, context, 0);
+
+ cmd_initrd->data = context;
+ cmd_initrdefi->data = context;
+
+ grub_file_close (file);
+ grub_free (kernel);
+ return 0;
+
fail:
if (file)
grub_file_close (file);
- if (grub_errno != GRUB_ERR_NONE)
- {
- grub_dl_unref (my_mod);
- loaded = 0;
- }
+ grub_dl_unref (my_mod);
- if (!loaded)
- {
- if (lh)
- kernel_free (linux_cmdline, lh->cmdline_size + 1);
+ if (lh)
+ kernel_free (cmdline, lh->cmdline_size + 1);
- kernel_free (kernel_mem, kernel_size);
- kernel_free (params, sizeof(*params));
- }
+ kernel_free (kernel_mem, kernel_size);
+ kernel_free (params, sizeof(*params));
+ grub_free (context);
grub_free (kernel);
return grub_errno;
}
-static grub_command_t cmd_linux, cmd_initrd;
-static grub_command_t cmd_linuxefi, cmd_initrdefi;
-
GRUB_MOD_INIT(linux)
{
cmd_linux =