# HG changeset patch
# User Christian Brabandt <cb@256bit.org>
# Date 1712078102 -7200
# Node ID a87c4383404a6ae9dfbaacf8019c8a26d58c5a00
# Parent  0e6516f5b03cbca0431d2cf5058f8948334e67f3
patch 9.1.0254: [security]: Heap buffer overflow when calling complete_add() in 'cfu'

Commit: https://github.com/vim/vim/commit/0a419e07a705675ac159218f42c1daa151d2ceea
Author: zeertzjq <zeertzjq@outlook.com>
Date:   Tue Apr 2 19:01:14 2024 +0200

    patch 9.1.0254: [security]: Heap buffer overflow when calling complete_add() in 'cfu'

    Problem:  [security]: Heap buffer overflow when calling complete_add()
              in the first call of 'completefunc'
    Solution: Call check_cursor() after calling 'completefunc' (zeertzjq)

    closes: #14391

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

diff --git a/src/insexpand.c b/src/insexpand.c
--- a/src/insexpand.c
+++ b/src/insexpand.c
@@ -2741,6 +2741,7 @@ expand_by_function(int type, char_u *bas
     --textlock;
 
     curwin->w_cursor = pos;	// restore the cursor position
+    check_cursor();  // make sure cursor position is valid, just in case
     validate_cursor();
     if (!EQUAL_POS(curwin->w_cursor, pos))
     {
@@ -4606,6 +4607,7 @@ get_userdefined_compl_info(colnr_T curs_
 
     State = save_State;
     curwin->w_cursor = pos;	// restore the cursor position
+    check_cursor();  // make sure cursor position is valid, just in case
     validate_cursor();
     if (!EQUAL_POS(curwin->w_cursor, pos))
     {
diff --git a/src/testdir/test_ins_complete.vim b/src/testdir/test_ins_complete.vim
--- a/src/testdir/test_ins_complete.vim
+++ b/src/testdir/test_ins_complete.vim
@@ -2429,4 +2429,26 @@ func Test_complete_changed_complete_info
   call StopVimInTerminal(buf)
 endfunc
 
+func Test_completefunc_first_call_complete_add()
+  new
+
+  func Complete(findstart, base) abort
+    if a:findstart
+      let col = col('.')
+      call complete_add('#')
+      return col - 1
+    else
+      return []
+    endif
+  endfunc
+
+  set completeopt=longest completefunc=Complete
+  " This used to cause heap-buffer-overflow
+  call assert_fails('call feedkeys("ifoo#\<C-X>\<C-U>", "xt")', 'E840:')
+
+  delfunc Complete
+  set completeopt& completefunc&
+  bwipe!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab nofoldenable
diff --git a/src/version.c b/src/version.c
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@ static char *(features[]) =
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    254,
+/**/
     253,
 /**/
     252,