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linux-next/drivers/firmware/efi/efibc.c
Jeremy Compostella 2e121d711a efibc: Fix excessive stack footprint warning
GCC complains about a newly added file for the EFI Bootloader Control:

  drivers/firmware/efi/efibc.c: In function 'efibc_set_variable':
  drivers/firmware/efi/efibc.c:53:1: error: the frame size of 2272 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

The problem is the declaration of a local variable of type struct
efivar_entry, which is by itself larger than the warning limit of 1024
bytes.

Use dynamic memory allocation instead of stack memory for the entry
object.

This patch also fixes a potential buffer overflow.

Reported-by: Ingo Molnar <mingo@kernel.org>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
[ Updated changelog to include GCC error ]
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1462570771-13324-3-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-05-07 07:06:13 +02:00

114 lines
2.8 KiB
C

/*
* efibc: control EFI bootloaders which obey LoaderEntryOneShot var
* Copyright (c) 2013-2016, Intel Corporation.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*/
#define pr_fmt(fmt) "efibc: " fmt
#include <linux/efi.h>
#include <linux/module.h>
#include <linux/reboot.h>
#include <linux/slab.h>
static void efibc_str_to_str16(const char *str, efi_char16_t *str16)
{
size_t i;
for (i = 0; i < strlen(str); i++)
str16[i] = str[i];
str16[i] = '\0';
}
static int efibc_set_variable(const char *name, const char *value)
{
int ret;
efi_guid_t guid = LINUX_EFI_LOADER_ENTRY_GUID;
struct efivar_entry *entry;
size_t size = (strlen(value) + 1) * sizeof(efi_char16_t);
if (size > sizeof(entry->var.Data)) {
pr_err("value is too large");
return -EINVAL;
}
entry = kmalloc(sizeof(*entry), GFP_KERNEL);
if (!entry) {
pr_err("failed to allocate efivar entry");
return -ENOMEM;
}
efibc_str_to_str16(name, entry->var.VariableName);
efibc_str_to_str16(value, (efi_char16_t *)entry->var.Data);
memcpy(&entry->var.VendorGuid, &guid, sizeof(guid));
ret = efivar_entry_set(entry,
EFI_VARIABLE_NON_VOLATILE
| EFI_VARIABLE_BOOTSERVICE_ACCESS
| EFI_VARIABLE_RUNTIME_ACCESS,
size, entry->var.Data, NULL);
if (ret)
pr_err("failed to set %s EFI variable: 0x%x\n",
name, ret);
kfree(entry);
return ret;
}
static int efibc_reboot_notifier_call(struct notifier_block *notifier,
unsigned long event, void *data)
{
const char *reason = "shutdown";
int ret;
if (event == SYS_RESTART)
reason = "reboot";
ret = efibc_set_variable("LoaderEntryRebootReason", reason);
if (ret || !data)
return NOTIFY_DONE;
efibc_set_variable("LoaderEntryOneShot", (char *)data);
return NOTIFY_DONE;
}
static struct notifier_block efibc_reboot_notifier = {
.notifier_call = efibc_reboot_notifier_call,
};
static int __init efibc_init(void)
{
int ret;
if (!efi_enabled(EFI_RUNTIME_SERVICES))
return -ENODEV;
ret = register_reboot_notifier(&efibc_reboot_notifier);
if (ret)
pr_err("unable to register reboot notifier\n");
return ret;
}
module_init(efibc_init);
static void __exit efibc_exit(void)
{
unregister_reboot_notifier(&efibc_reboot_notifier);
}
module_exit(efibc_exit);
MODULE_AUTHOR("Jeremy Compostella <jeremy.compostella@intel.com>");
MODULE_AUTHOR("Matt Gumbel <matthew.k.gumbel@intel.com");
MODULE_DESCRIPTION("EFI Bootloader Control");
MODULE_LICENSE("GPL v2");