From ab46f48dde8aa70e44a2fc2d2a1b81ae703d4981 Mon Sep 17 00:00:00 2001
From: Willow Herring <31960031+ReFil@users.noreply.github.com>
Date: Fri, 16 Jan 2026 23:55:13 +0000
Subject: [PATCH] fix(keymap): Fix overflow in get/set bindings (#3205)

With the binding referenced to as uint8_t the keymap would be incorrect if more than 256 positions were in use, going to a uint16_t gives large enough headroom to not have to worry
---
 app/include/zmk/keymap.h | 4 ++--
 app/src/keymap.c         | 6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/app/include/zmk/keymap.h b/app/include/zmk/keymap.h
index c7b2681d5..26fd2d160 100644
--- a/app/include/zmk/keymap.h
+++ b/app/include/zmk/keymap.h
@@ -55,8 +55,8 @@ int zmk_keymap_layer_to(zmk_keymap_layer_id_t layer, bool locking);
 const char *zmk_keymap_layer_name(zmk_keymap_layer_id_t layer);
 
 const struct zmk_behavior_binding *zmk_keymap_get_layer_binding_at_idx(zmk_keymap_layer_id_t layer,
-                                                                       uint8_t binding_idx);
-int zmk_keymap_set_layer_binding_at_idx(zmk_keymap_layer_id_t layer, uint8_t binding_idx,
+                                                                       uint16_t binding_idx);
+int zmk_keymap_set_layer_binding_at_idx(zmk_keymap_layer_id_t layer, uint16_t binding_idx,
                                         const struct zmk_behavior_binding binding);
 
 #if IS_ENABLED(CONFIG_ZMK_KEYMAP_LAYER_REORDERING)
diff --git a/app/src/keymap.c b/app/src/keymap.c
index a291d5f01..547d6612f 100644
--- a/app/src/keymap.c
+++ b/app/src/keymap.c
@@ -242,7 +242,7 @@ const char *zmk_keymap_layer_name(zmk_keymap_layer_id_t layer_id) {
 }
 
 const struct zmk_behavior_binding *
-zmk_keymap_get_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint8_t binding_idx) {
+zmk_keymap_get_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint16_t binding_idx) {
     if (binding_idx >= ZMK_KEYMAP_LEN) {
         return NULL;
     }
@@ -277,7 +277,7 @@ zmk_keymap_get_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint8_t bind
 
 static uint8_t zmk_keymap_layer_pending_changes[ZMK_KEYMAP_LAYERS_LEN][PENDING_ARRAY_SIZE];
 
-int zmk_keymap_set_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint8_t binding_idx,
+int zmk_keymap_set_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint16_t binding_idx,
                                         struct zmk_behavior_binding binding) {
     if (binding_idx >= ZMK_KEYMAP_LEN) {
         return -EINVAL;
@@ -322,7 +322,7 @@ int zmk_keymap_set_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint8_t
 
 #else
 
-int zmk_keymap_set_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint8_t binding_idx,
+int zmk_keymap_set_layer_binding_at_idx(zmk_keymap_layer_id_t layer_id, uint16_t binding_idx,
                                         struct zmk_behavior_binding binding) {
     return -ENOTSUP;
 }