efivars: pstore: Do not check size when erasing variable

[pandora-kernel.git] / drivers / firmware / efivars.c

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 480d2c5..b15c0aa 100644 (file)
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -159,6 +159,7 @@ efivar_create_sysfs_entry(struct efivars *efivars,
 
 static void efivar_update_sysfs_entries(struct work_struct *);
 static DECLARE_WORK(efivar_work, efivar_update_sysfs_entries);
+static bool efivar_wq_enabled = true;
 
 /* Return the number of unicode characters in data */
 static unsigned long
@@ -786,19 +787,21 @@ static int efi_pstore_write(enum pstore_type_id type, u64 *id,
 
        spin_lock_irqsave(&efivars->lock, flags);
 
-       /*
-        * Check if there is a space enough to log.
-        * size: a size of logging data
-        * DUMP_NAME_LEN * 2: a maximum size of variable name
-        */
+       if (size) {
+               /*
+                * Check if there is a space enough to log.
+                * size: a size of logging data
+                * DUMP_NAME_LEN * 2: a maximum size of variable name
+                */
 
-       status = check_var_size_locked(efivars, PSTORE_EFI_ATTRIBUTES,
-                                        size + DUMP_NAME_LEN * 2);
+               status = check_var_size_locked(efivars, PSTORE_EFI_ATTRIBUTES,
+                                              size + DUMP_NAME_LEN * 2);
 
-       if (status) {
-               spin_unlock_irqrestore(&efivars->lock, flags);
-               *id = part;
-               return -ENOSPC;
+               if (status) {
+                       spin_unlock_irqrestore(&efivars->lock, flags);
+                       *id = part;
+                       return -ENOSPC;
+               }
        }
 
        for (i = 0; i < DUMP_NAME_LEN; i++)
@@ -842,7 +845,8 @@ static int efi_pstore_write(enum pstore_type_id type, u64 *id,
        if (found)
                efivar_unregister(found);
 
-       schedule_work(&efivar_work);
+       if (efivar_wq_enabled)
+               schedule_work(&efivar_work);
 
        *id = part;
        return ret;
@@ -1043,6 +1047,31 @@ static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor)
        return found;
 }
 
+/*
+ * Returns the size of variable_name, in bytes, including the
+ * terminating NULL character, or variable_name_size if no NULL
+ * character is found among the first variable_name_size bytes.
+ */
+static unsigned long var_name_strnsize(efi_char16_t *variable_name,
+                                      unsigned long variable_name_size)
+{
+       unsigned long len;
+       efi_char16_t c;
+
+       /*
+        * The variable name is, by definition, a NULL-terminated
+        * string, so make absolutely sure that variable_name_size is
+        * the value we expect it to be. If not, return the real size.
+        */
+       for (len = 2; len <= variable_name_size; len += sizeof(c)) {
+               c = variable_name[(len / sizeof(c)) - 1];
+               if (!c)
+                       break;
+       }
+
+       return min(len, variable_name_size);
+}
+
 static void efivar_update_sysfs_entries(struct work_struct *work)
 {
        struct efivars *efivars = &__efivars;
@@ -1083,10 +1112,13 @@ static void efivar_update_sysfs_entries(struct work_struct *work)
                if (!found) {
                        kfree(variable_name);
                        break;
-               } else
+               } else {
+                       variable_name_size = var_name_strnsize(variable_name,
+                                                              variable_name_size);
                        efivar_create_sysfs_entry(efivars,
                                                  variable_name_size,
                                                  variable_name, &vendor);
+               }
        }
 }
 
@@ -1277,6 +1309,35 @@ void unregister_efivars(struct efivars *efivars)
 }
 EXPORT_SYMBOL_GPL(unregister_efivars);
 
+/*
+ * Print a warning when duplicate EFI variables are encountered and
+ * disable the sysfs workqueue since the firmware is buggy.
+ */
+static void dup_variable_bug(efi_char16_t *s16, efi_guid_t *vendor_guid,
+                            unsigned long len16)
+{
+       size_t i, len8 = len16 / sizeof(efi_char16_t);
+       char *s8;
+
+       /*
+        * Disable the workqueue since the algorithm it uses for
+        * detecting new variables won't work with this buggy
+        * implementation of GetNextVariableName().
+        */
+       efivar_wq_enabled = false;
+
+       s8 = kzalloc(len8, GFP_KERNEL);
+       if (!s8)
+               return;
+
+       for (i = 0; i < len8; i++)
+               s8[i] = s16[i];
+
+       printk(KERN_WARNING "efivars: duplicate variable: %s-%pUl\n",
+              s8, vendor_guid);
+       kfree(s8);
+}
+
 int register_efivars(struct efivars *efivars,
                     const struct efivar_operations *ops,
                     struct kobject *parent_kobj)
@@ -1317,6 +1378,24 @@ int register_efivars(struct efivars *efivars,
                                                &vendor_guid);
                switch (status) {
                case EFI_SUCCESS:
+                       variable_name_size = var_name_strnsize(variable_name,
+                                                              variable_name_size);
+
+                       /*
+                        * Some firmware implementations return the
+                        * same variable name on multiple calls to
+                        * get_next_variable(). Terminate the loop
+                        * immediately as there is no guarantee that
+                        * we'll ever see a different variable name,
+                        * and may end up looping here forever.
+                        */
+                       if (variable_is_present(variable_name, &vendor_guid)) {
+                               dup_variable_bug(variable_name, &vendor_guid,
+                                                variable_name_size);
+                               status = EFI_NOT_FOUND;
+                               break;
+                       }
+
                        efivar_create_sysfs_entry(efivars,
                                                  variable_name_size,
                                                  variable_name,