SDL_image: stb_image.h: apply mainstream PR/1736 (38c5b)

From 38c5b84844574306dfe6f00bd3bcb81447efe138 Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Wed, 23 Apr 2025 17:50:10 +0300
Subject: [PATCH] stb_image.h: apply mainstream PR/1736

Fix root-cause of CVE-2021-45340 : dereference of NULL ptr.
Patch authored by Henner Zeller <h.zeller@acm.org>
Mainstream pull request: https://github.com/nothings/stb/pull/1736

(cherry picked from commit d345579624ebb60882500c0eabc0aa17122e286b)
---
 src/stb_image.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/stb_image.h b/src/stb_image.h
index 7147a7a1..6daf9eab 100644
--- a/src/stb_image.h
+++ b/src/stb_image.h
@@ -100,7 +100,7 @@ RECENT REVISION HISTORY:
  Bug & warning fixes
     Marc LeBlanc            David Woo          Guillaume George     Martins Mozeiko
     Christpher Lloyd        Jerry Jansson      Joseph Thomson       Blazej Dariusz Roszkowski
-    Phil Jordan                                Dave Moore           Roy Eltham
+    Phil Jordan             Henner Zeller      Dave Moore           Roy Eltham
     Hayaki Saito            Nathan Reed        Won Chun
     Luke Graham             Johan Duparc       Nick Verigakis       the Horde3D community
     Thomas Ruf              Ronny Chevalier                         github:rlyeh
@@ -1895,6 +1895,7 @@ static unsigned char *stbi__convert_format(unsigned char *data, int img_n, int r
    int i,j;
    unsigned char *good;
 
+   if (data == NULL) return data;
    if (req_comp == img_n) return data;
    STBI_ASSERT(req_comp >= 1 && req_comp <= 4);