reset: Fix crash when freeing non-existent optional resets

When obtaining one or more optional resets, non-existent resets are
stored as NULL pointers, and all related error and cleanup paths need to
take this into account.

Currently only reset_control_put() and reset_control_bulk_put()
get this right.  All of __reset_control_bulk_get(),
of_reset_control_array_get(), and reset_control_array_put() lack the
proper checking, causing NULL pointer dereferences on failure or
release.

Fix this by moving the existing check from reset_control_bulk_put() to
__reset_control_put_internal(), so it applies to all callers.
The double check in reset_control_put() doesn't hurt.

Fixes: 17c82e2 ("reset: Add APIs to manage array of resets")
Fixes: 48d7139 ("reset: Add reset_control_bulk API")
Signed-off-by: Geert Uytterhoeven <[email protected]>
Link: https://lore.kernel.org/r/2440edae7ca8534628cdbaf559ded288f2998178.1701276806.git.geert+renesas@glider.be
Signed-off-by: Philipp Zabel <[email protected]>

Author: geertu

drivers/reset/core.c

@@ -807,6 +807,9 @@ static void __reset_control_put_internal(struct reset_control *rstc)
 {
 	lockdep_assert_held(&reset_list_mutex);
 
+	if (IS_ERR_OR_NULL(rstc))
+		return;
+
 	kref_put(&rstc->refcnt, __reset_control_release);
 }
 
@@ -1017,11 +1020,8 @@ EXPORT_SYMBOL_GPL(reset_control_put);
 void reset_control_bulk_put(int num_rstcs, struct reset_control_bulk_data *rstcs)
 {
 	mutex_lock(&reset_list_mutex);
-	while (num_rstcs--) {
-		if (IS_ERR_OR_NULL(rstcs[num_rstcs].rstc))
-			continue;
+	while (num_rstcs--)
 		__reset_control_put_internal(rstcs[num_rstcs].rstc);
-	}
 	mutex_unlock(&reset_list_mutex);
 }
 EXPORT_SYMBOL_GPL(reset_control_bulk_put);