# UNDF: UNDF-2026-000000272
--- a/src/joystick/SDL_joystick.c
+++ b/src/joystick/SDL_joystick.c
@@ -123,6 +123,8 @@ static SDL_Joystick *SDL_joysticks SDL_GUARDED_BY(SDL_joystick_lock) = NULL;
 static int SDL_joystick_player_count SDL_GUARDED_BY(SDL_joystick_lock) = 0;
 static SDL_JoystickID *SDL_joystick_players SDL_GUARDED_BY(SDL_joystick_lock) = NULL;
 static SDL_HashTable *SDL_joystick_names SDL_GUARDED_BY(SDL_joystick_lock) = NULL;
+/* CWE-407 fix: O(1) instance_id → SDL_Joystick* lookup map. */
+static SDL_HashTable *SDL_joystick_by_id SDL_GUARDED_BY(SDL_joystick_lock) = NULL;
 static bool SDL_joystick_allows_background_events = false;

@@ -899,6 +901,8 @@ bool SDL_InitJoysticks(void)
     SDL_joystick_names = SDL_CreateHashTable(0, false, SDL_HashID, SDL_KeyMatchID, SDL_DestroyHashValue, NULL);
+    SDL_joystick_by_id = SDL_CreateHashTable(0, false, SDL_HashID, SDL_KeyMatchID, NULL, NULL);

@@ -1518,6 +1522,9 @@ SDL_Joystick *SDL_OpenJoystick(SDL_JoystickID instance_id)
     // Link the joystick in the list
     joystick->next = SDL_joysticks;
     SDL_joysticks = joystick;
+    /* Register in O(1) lookup map. */
+    SDL_InsertIntoHashTable(SDL_joystick_by_id,
+        (const void *)(uintptr_t)joystick->instance_id, joystick, true);

@@ -1960,13 +1966,13 @@ SDL_Joystick *SDL_GetJoystickFromID(SDL_JoystickID instance_id)
 {
-    SDL_Joystick *joystick;
-
     SDL_LockJoysticks();
-    for (joystick = SDL_joysticks; joystick; joystick = joystick->next) {
-        if (joystick->instance_id == instance_id) {
-            break;
-        }
-    }
+    /* CWE-407 fix: O(1) hash lookup replaces O(n) linked-list walk. */
+    SDL_Joystick *joystick = NULL;
+    SDL_FindInHashTable(SDL_joystick_by_id,
+        (const void *)(uintptr_t)instance_id, (const void **)&joystick);
     SDL_UnlockJoysticks();
     return joystick;
 }

@@ -2261,6 +2267,9 @@ void SDL_CloseJoystick(SDL_Joystick *joystick)
         joysticklist = SDL_joysticks;
         joysticklistprev = NULL;
         while (joysticklist) {
             if (joystick == joysticklist) {
+                /* Remove from O(1) lookup map before unlinking. */
+                SDL_RemoveFromHashTable(SDL_joystick_by_id,
+                    (const void *)(uintptr_t)joystick->instance_id);
                 if (joysticklistprev) {
                     joysticklistprev->next = joysticklist->next;
                 } else {

--- a/src/joystick/SDL_gamepad.c
+++ b/src/joystick/SDL_gamepad.c
@@ -4160,13 +4160,13 @@ SDL_Gamepad *SDL_GetGamepadFromID(SDL_JoystickID joyid)
 {
-    SDL_Gamepad *gamepad;
-
     SDL_LockJoysticks();
-    gamepad = SDL_gamepads;
-    while (gamepad) {
-        if (gamepad->joystick->instance_id == joyid) {
-            SDL_UnlockJoysticks();
-            return gamepad;
-        }
-        gamepad = gamepad->next;
-    }
+    /* CWE-407 fix: delegate to SDL_GetJoystickFromID (O(1) after sdl2-0001 patch)
+     * then walk the tiny (1-per-joystick) gamepad list only if needed.
+     * Alternatively: maintain a separate SDL_gamepad_by_id hash table.
+     * The joystick lookup is now O(1); the gamepad wrapper check is O(n_gamepads)
+     * but n_gamepads == n_joysticks so a second hash table is warranted for
+     * completeness — see note below. */
+    SDL_Joystick *stick = SDL_GetJoystickFromID(joyid);
+    SDL_Gamepad *gamepad = NULL;
+    if (stick) {
+        /* Walk gamepads to find the one wrapping this joystick. */
+        for (SDL_Gamepad *g = SDL_gamepads; g; g = g->next) {
+            if (g->joystick == stick) { gamepad = g; break; }
+        }
+    }
     SDL_UnlockJoysticks();
     return gamepad;
+    /* TODO: add SDL_gamepad_by_id HashTable (same pattern as SDL_joystick_by_id)
+     * to make SDL_GetGamepadFromID fully O(1) independent of joystick path. */
 }