From 48e80c8f269365c3320f42c0bdad77369a447fc4 Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <anonymous.maarten@gmail.com>
Date: Thu, 2 Apr 2026 19:25:54 +0200
Subject: [PATCH] memcpy with a NULL src/dst argument is UB

malloc of UBSAN returns NULL when allocating 0 bytes, causing a call to memcpy(NULL, xxx, 0);
---
 src/video/SDL_video.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/video/SDL_video.c b/src/video/SDL_video.c
index 6cb30d83a8..a338645c96 100644
--- a/src/video/SDL_video.c
+++ b/src/video/SDL_video.c
@@ -1352,7 +1352,9 @@ SDL_DisplayMode **SDL_GetFullscreenDisplayModes(SDL_DisplayID displayID, int *co
     result = (SDL_DisplayMode **)SDL_malloc((num_modes + 1) * sizeof(*result) + num_modes * sizeof(**result));
     if (result) {
         SDL_DisplayMode *modes = (SDL_DisplayMode *)((Uint8 *)result + ((num_modes + 1) * sizeof(*result)));
-        SDL_memcpy(modes, display->fullscreen_modes, num_modes * sizeof(*modes));
+        if (num_modes) {
+            SDL_memcpy(modes, display->fullscreen_modes, num_modes * sizeof(*modes));
+        }
         for (i = 0; i < num_modes; ++i) {
             result[i] = modes++;
         }