From 52e88e89542cfd3e6e87ca10ebc70ae1048b2890 Mon Sep 17 00:00:00 2001
From: Simone Gotti <simone.gotti@gmail.com>
Date: Fri, 29 Mar 2024 15:16:55 +0100
Subject: [PATCH] imageio: fix issues/crash on png with transparency

If a png has a transparency chunk (tRNS), after converting the
transparency to alpha we should also strip alpha (color_type is not
updated with PNG_COLOR_MASK_ALPHA flag set) or the row parsing will
return also the alpha channel causing a memory overflow.
---
 rtengine/imageio.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rtengine/imageio.cc b/rtengine/imageio.cc
index e2c6c1310..f096213dc 100644
--- a/rtengine/imageio.cc
+++ b/rtengine/imageio.cc
@@ -285,6 +285,7 @@ int ImageIO::loadPNG  (const Glib::ustring &fname)
 
     if (png_get_valid(png, info, PNG_INFO_tRNS)) {
         png_set_tRNS_to_alpha(png);
+        png_set_strip_alpha(png);
     }
 
     if (color_type & PNG_COLOR_MASK_ALPHA) {