Fixed bug 5155 - HIDAPI_JoystickDisconnected incorrect array shift

Anthony Pesch

I was looking into my own input bug and noticed an issue in the HIDAPI code while looking over it. I don't have a controller that goes down this path to test and try to provoke the issue, but it looks pretty straight forward.

The memmove to shift the joystick id array on disconnect isn't scaling the size by sizeof(SDL_JoystickID), likely corrupting the ids on disconnect.

src/joystick/hidapi/SDL_hidapijoystick.c

@@ -631,7 +631,7 @@ HIDAPI_JoystickConnected(SDL_HIDAPI_Device *device, SDL_JoystickID *pJoystickID,
 void
 HIDAPI_JoystickDisconnected(SDL_HIDAPI_Device *device, SDL_JoystickID joystickID, SDL_bool is_external)
 {
-    int i;
+    int i, size;
 
     for (i = 0; i < device->num_joysticks; ++i) {
         if (device->joysticks[i] == joystickID) {
@@ -640,8 +640,10 @@ HIDAPI_JoystickDisconnected(SDL_HIDAPI_Device *device, SDL_JoystickID joystickID
                 HIDAPI_JoystickClose(joystick);
             }
 
-            SDL_memmove(&device->joysticks[i], &device->joysticks[i+1], device->num_joysticks - i - 1);
+            size = (device->num_joysticks - i - 1) * sizeof(SDL_JoystickID);
+            SDL_memmove(&device->joysticks[i], &device->joysticks[i+1], size);
             --device->num_joysticks;
+
             if (!is_external) {
                 --SDL_HIDAPI_numjoysticks;
             }