libsixel: fix CVE-2021-45340 (#372312)

pkgs/by-name/li/libsixel/fix-CVE-2021-45340.patch

···
+diff --git a/src/stb_image.h b/src/stb_image.h
+index f12c30b..526281c 100644
+--- a/src/stb_image.h
++++ b/src/stb_image.h
+@@ -1534,6 +1534,7 @@ 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);
+ 

pkgs/by-name/li/libsixel/package.nix

···
     sha256 = "1nny4295ipy4ajcxmmh04c796hcds0y7z7rv3qd17mj70y8j0r2d";
   };
 
+  patches = [
+    # https://github.com/NixOS/nixpkgs/issues/160670
+    ./fix-CVE-2021-45340.patch
+  ];
+
   buildInputs = [
     gdk-pixbuf
     gd
···
   meta = with lib; {
     description = "SIXEL library for console graphics, and converter programs";
     homepage = "https://github.com/libsixel/libsixel";
-    maintainers = [ ];
+    maintainers = with lib.maintainers; [ hzeller ];
     license = licenses.mit;
     platforms = platforms.unix;
   };