1 files changed, 47 insertions, 1 deletions

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 1e9d9b9d7a12..d64661fda4fd 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -170,6 +170,7 @@ 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
@@ -1444,7 +1445,7 @@ static int efi_pstore_write(enum pstore_type_id type,
 
         spin_unlock_irqrestore(&efivars->lock, flags);
 
-        if (reason == KMSG_DUMP_OOPS)
+        if (reason == KMSG_DUMP_OOPS && efivar_wq_enabled)
                 schedule_work(&efivar_work);
 
         *id = part;
@@ -1975,6 +1976,35 @@ 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)
@@ -2025,6 +2055,22 @@ int register_efivars(struct efivars *efivars,
                 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,