patch 9.2.0039: potential integer underflow in screen_line()

Problem:  In screen_line(), there is a potential integer underflow when
          accessing ScreenAttrs[off_to - 1] if off_to is zero.
          (Coverity CID 1681430, after v9.2.0017)
Solution: Add a check to ensure off_to > 0 before accessing the
          previous attribute index.

related: #19272
closes:  #19479

Signed-off-by: Christian Brabandt <cb@256bit.org>

diff --git a/src/screen.c b/src/screen.c
index 6e6f11b70b6399b51be0ab4db3bec5e1b7e0bc59..b3fe3705e03462702eaf2fb001afea6cba98f51c 100644 (file)
--- a/src/screen.c
+++ b/src/screen.c
@@ -848,7 +848,7 @@ skip_opacity:
 #ifdef FEAT_GUI
                && !gui.in_use
 #endif
-               && col + coloff > 0)
+               && col + coloff > 0 && off_to > 0)
        {
            if (ScreenAttrs[off_to] == ScreenAttrs[off_to - 1])
            {

diff --git a/src/version.c b/src/version.c
index 871f3b23926524c6cf03915e7d9c2f0e149aaec4..336ac8894fb6daca4235a50c7b196e9a87c127e4 100644 (file)
--- a/src/version.c
+++ b/src/version.c
@@ -734,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    39,
 /**/
     38,
 /**/