ACPI / bus: Do not traverse through non-existed device table

When __acpi_match_device() is called it would be possible to have
ACPI ID table a NULL pointer. To avoid potential dereference,
check for this before traverse.

While here, remove redundant 'else'.

Note, this patch implies a bit of refactoring acpi_of_match_device()
to return pointer to OF ID when matched followed by refactoring
__acpi_match_device() to return either ACPI or OF ID when matches.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 676c978..f1384e1 100644 (file)
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -660,13 +660,15 @@ struct acpi_device *acpi_companion_match(const struct device *dev)
  * acpi_of_match_device - Match device object using the "compatible" property.
  * @adev: ACPI device object to match.
  * @of_match_table: List of device IDs to match against.
+ * @of_id: OF ID if matched
  *
  * If @dev has an ACPI companion which has ACPI_DT_NAMESPACE_HID in its list of
  * identifiers and a _DSD object with the "compatible" property, use that
  * property to match against the given list of identifiers.
  */
 static bool acpi_of_match_device(struct acpi_device *adev,
-                                const struct of_device_id *of_match_table)
+                                const struct of_device_id *of_match_table,
+                                const struct of_device_id **of_id)
 {
        const union acpi_object *of_compatible, *obj;
        int i, nval;
@@ -690,8 +692,11 @@ static bool acpi_of_match_device(struct acpi_device *adev,
                const struct of_device_id *id;
 
                for (id = of_match_table; id->compatible[0]; id++)
-                       if (!strcasecmp(obj->string.pointer, id->compatible))
+                       if (!strcasecmp(obj->string.pointer, id->compatible)) {
+                               if (of_id)
+                                       *of_id = id;
                                return true;
+                       }
        }
 
        return false;
@@ -762,10 +767,11 @@ static bool __acpi_match_device_cls(const struct acpi_device_id *id,
        return true;
 }
 
-static const struct acpi_device_id *__acpi_match_device(
-       struct acpi_device *device,
-       const struct acpi_device_id *ids,
-       const struct of_device_id *of_ids)
+static bool __acpi_match_device(struct acpi_device *device,
+                               const struct acpi_device_id *acpi_ids,
+                               const struct of_device_id *of_ids,
+                               const struct acpi_device_id **acpi_id,
+                               const struct of_device_id **of_id)
 {
        const struct acpi_device_id *id;
        struct acpi_hardware_id *hwid;
@@ -775,30 +781,32 @@ static const struct acpi_device_id *__acpi_match_device(
         * driver for it.
         */
        if (!device || !device->status.present)
-               return NULL;
+               return false;
 
        list_for_each_entry(hwid, &device->pnp.ids, list) {
                /* First, check the ACPI/PNP IDs provided by the caller. */
-               for (id = ids; id->id[0] || id->cls; id++) {
-                       if (id->id[0] && !strcmp((char *) id->id, hwid->id))
-                               return id;
-                       else if (id->cls && __acpi_match_device_cls(id, hwid))
-                               return id;
+               if (acpi_ids) {
+                       for (id = acpi_ids; id->id[0] || id->cls; id++) {
+                               if (id->id[0] && !strcmp((char *)id->id, hwid->id))
+                                       goto out_acpi_match;
+                               if (id->cls && __acpi_match_device_cls(id, hwid))
+                                       goto out_acpi_match;
+                       }
                }
 
                /*
                 * Next, check ACPI_DT_NAMESPACE_HID and try to match the
                 * "compatible" property if found.
-                *
-                * The id returned by the below is not valid, but the only
-                * caller passing non-NULL of_ids here is only interested in
-                * whether or not the return value is NULL.
                 */
-               if (!strcmp(ACPI_DT_NAMESPACE_HID, hwid->id)
-                   && acpi_of_match_device(device, of_ids))
-                       return id;
+               if (!strcmp(ACPI_DT_NAMESPACE_HID, hwid->id))
+                       return acpi_of_match_device(device, of_ids, of_id);
        }
-       return NULL;
+       return false;
+
+out_acpi_match:
+       if (acpi_id)
+               *acpi_id = id;
+       return true;
 }
 
 /**
@@ -815,7 +823,10 @@ static const struct acpi_device_id *__acpi_match_device(
 const struct acpi_device_id *acpi_match_device(const struct acpi_device_id *ids,
                                               const struct device *dev)
 {
-       return __acpi_match_device(acpi_companion_match(dev), ids, NULL);
+       const struct acpi_device_id *id = NULL;
+
+       __acpi_match_device(acpi_companion_match(dev), ids, NULL, &id, NULL);
+       return id;
 }
 EXPORT_SYMBOL_GPL(acpi_match_device);
 
@@ -840,7 +851,7 @@ EXPORT_SYMBOL_GPL(acpi_get_match_data);
 int acpi_match_device_ids(struct acpi_device *device,
                          const struct acpi_device_id *ids)
 {
-       return __acpi_match_device(device, ids, NULL) ? 0 : -ENOENT;
+       return __acpi_match_device(device, ids, NULL, NULL, NULL) ? 0 : -ENOENT;
 }
 EXPORT_SYMBOL(acpi_match_device_ids);
 
@@ -849,10 +860,12 @@ bool acpi_driver_match_device(struct device *dev,
 {
        if (!drv->acpi_match_table)
                return acpi_of_match_device(ACPI_COMPANION(dev),
-                                           drv->of_match_table);
+                                           drv->of_match_table,
+                                           NULL);
 
-       return !!__acpi_match_device(acpi_companion_match(dev),
-                                    drv->acpi_match_table, drv->of_match_table);
+       return __acpi_match_device(acpi_companion_match(dev),
+                                  drv->acpi_match_table, drv->of_match_table,
+                                  NULL, NULL);
 }
 EXPORT_SYMBOL_GPL(acpi_driver_match_device);