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efivars: only check for duplicates on the registered list 

variable_is_present() accesses '__efivars' directly, but when called via
gsmi_init() Michel reports observing the following crash,

  BUG: unable to handle kernel NULL pointer dereference at (null)
  IP: variable_is_present+0x55/0x170
  Call Trace:
    register_efivars+0x106/0x370
    gsmi_init+0x2ad/0x3da
    do_one_initcall+0x3f/0x170

The reason for the crash is that '__efivars' hasn't been initialised nor
has it been registered with register_efivars() by the time the google
EFI SMI driver runs.  The gsmi code uses its own struct efivars, and
therefore, a different variable list.  Fix the above crash by passing
the registered struct efivars to variable_is_present(), so that we
traverse the correct list.

Reported-by: Michel Lespinasse <walken@google.com>
Tested-by: Michel Lespinasse <walken@google.com>
Cc: Mike Waychison <mikew@google.com>
Cc: Matthew Garrett <matthew.garrett@nebula.com>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matt Fleming 2013-04-26 10:10:55 +01:00 committed by Linus Torvalds
parent 37b7f3c765
commit f464246d85
1 changed files with 7 additions and 5 deletions
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12
drivers/firmware/efivars.c
View File

@ -1628,10 +1628,11 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
return count;
}
static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor)
static bool variable_is_present(struct efivars *efivars,
efi_char16_t *variable_name,
efi_guid_t *vendor)
{
struct efivar_entry *entry, *n;
struct efivars *efivars = &__efivars;
unsigned long strsize1, strsize2;
bool found = false;
@ -1703,8 +1704,8 @@ static void efivar_update_sysfs_entries(struct work_struct *work)
if (status != EFI_SUCCESS) {
break;
} else {
if (!variable_is_present(variable_name,
&vendor)) {
if (!variable_is_present(efivars,
variable_name, &vendor)) {
found = true;
break;
}
@ -2008,7 +2009,8 @@ int register_efivars(struct efivars *efivars,
* we'll ever see a different variable name,
* and may end up looping here forever.
*/
if (variable_is_present(variable_name, &vendor_guid)) {
if (variable_is_present(efivars, variable_name,
&vendor_guid)) {
dup_variable_bug(variable_name, &vendor_guid,
variable_name_size);
status = EFI_NOT_FOUND;