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efibc: Fix excessive stack footprint warning

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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>
This commit is contained in:
Jeremy Compostella 2016-05-06 22:39:28 +01:00 committed by Ingo Molnar
parent 62075e5818
commit 2e121d711a
1 changed files with 23 additions and 11 deletions
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34
drivers/firmware/efi/efibc.c
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@ -17,6 +17,7 @@
#include <linux/efi.h> #include <linux/efi.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/reboot.h> #include <linux/reboot.h>
#include <linux/slab.h>
static void efibc_str_to_str16(const char *str, efi_char16_t *str16) static void efibc_str_to_str16(const char *str, efi_char16_t *str16)
{ {
@ -28,41 +29,52 @@ static void efibc_str_to_str16(const char *str, efi_char16_t *str16)
str16[i] = '\0'; str16[i] = '\0';
} }
static void efibc_set_variable(const char *name, const char *value) static int efibc_set_variable(const char *name, const char *value)
{ {
int ret; int ret;
efi_guid_t guid = LINUX_EFI_LOADER_ENTRY_GUID; efi_guid_t guid = LINUX_EFI_LOADER_ENTRY_GUID;
struct efivar_entry entry; struct efivar_entry *entry;
size_t size = (strlen(value) + 1) * sizeof(efi_char16_t); size_t size = (strlen(value) + 1) * sizeof(efi_char16_t);
if (size > sizeof(entry.var.Data)) if (size > sizeof(entry->var.Data)) {
pr_err("value is too large"); pr_err("value is too large");
return -EINVAL;
}
efibc_str_to_str16(name, entry.var.VariableName); entry = kmalloc(sizeof(*entry), GFP_KERNEL);
efibc_str_to_str16(value, (efi_char16_t *)entry.var.Data); if (!entry) {
memcpy(&entry.var.VendorGuid, &guid, sizeof(guid)); pr_err("failed to allocate efivar entry");
return -ENOMEM;
}
ret = efivar_entry_set(&entry, 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_NON_VOLATILE
| EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS
| EFI_VARIABLE_RUNTIME_ACCESS, | EFI_VARIABLE_RUNTIME_ACCESS,
size, entry.var.Data, NULL); size, entry->var.Data, NULL);
if (ret) if (ret)
pr_err("failed to set %s EFI variable: 0x%x\n", pr_err("failed to set %s EFI variable: 0x%x\n",
name, ret); name, ret);
kfree(entry);
return ret;
} }
static int efibc_reboot_notifier_call(struct notifier_block *notifier, static int efibc_reboot_notifier_call(struct notifier_block *notifier,
unsigned long event, void *data) unsigned long event, void *data)
{ {
const char *reason = "shutdown"; const char *reason = "shutdown";
int ret;
if (event == SYS_RESTART) if (event == SYS_RESTART)
reason = "reboot"; reason = "reboot";
efibc_set_variable("LoaderEntryRebootReason", reason); ret = efibc_set_variable("LoaderEntryRebootReason", reason);
if (ret || !data)
if (!data)
return NOTIFY_DONE; return NOTIFY_DONE;
efibc_set_variable("LoaderEntryOneShot", (char *)data); efibc_set_variable("LoaderEntryOneShot", (char *)data);