# HG changeset patch
# User Christian Brabandt <cb@256bit.org>
# Date 1702217761 -3600
# Node ID 242b964d626947c9e8dc16d9f8f12e9bbf3205dd
# Parent  e6c291944e1810aafe78250b8e60c843bc462f91
patch 9.0.2140: [security]: use-after-free in win-enter

Commit: https://github.com/vim/vim/commit/eec0c2b3a4cfab93dd8d4adaa60638d47a2bbc8a
Author: Christian Brabandt <cb@256bit.org>
Date:   Tue Nov 28 22:03:48 2023 +0100

    patch 9.0.2140: [security]: use-after-free in win-enter

    Problem:  [security]: use-after-free in win-enter
    Solution: validate window pointer before calling win_enter()

    win_goto() may stop visual mode, if it is active. However, this may in
    turn trigger the ModeChanged autocommand, which could potentially free
    the wp pointer which was valid before now became stale and points to now
    freed memory.

    So before calling win_enter(), let's verify one more time, that the
    wp pointer still points to a valid window structure.

    Reported by @henices, thanks!

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

diff --git a/src/testdir/crash/poc_win_enter_ext b/src/testdir/crash/poc_win_enter_ext
new file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..73f53b575b699046d6bdc5402083dfa9c278769a
GIT binary patch
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diff --git a/src/testdir/test_crash.vim b/src/testdir/test_crash.vim
--- a/src/testdir/test_crash.vim
+++ b/src/testdir/test_crash.vim
@@ -128,6 +128,13 @@ func Test_crash1_2()
     \ '  && echo "crash 1: [OK]" > '.. result .. "\<cr>")
   call TermWait(buf, 150)
 
+  let file = 'crash/poc_win_enter_ext'
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
+  let args = printf(cmn_args, vim, file)
+  call term_sendkeys(buf, args ..
+    \ '  && echo "crash 2: [OK]" >> '.. result .. "\<cr>")
+  call TermWait(buf, 350)
+
   " clean up
   exe buf .. "bw!"
 
@@ -135,6 +142,7 @@ func Test_crash1_2()
 
   let expected = [
       \ 'crash 1: [OK]',
+      \ 'crash 2: [OK]',
       \ ]
 
   call assert_equal(expected, getline(1, '$'))
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 */
 /**/
+    2140,
+/**/
     2139,
 /**/
     2138,
diff --git a/src/window.c b/src/window.c
--- a/src/window.c
+++ b/src/window.c
@@ -5013,6 +5013,7 @@ tabpage_move(int nr)
  * Go to another window.
  * When jumping to another buffer, stop Visual mode.  Do this before
  * changing windows so we can yank the selection into the '*' register.
+ * (note: this may trigger ModeChanged autocommand!)
  * When jumping to another window on the same buffer, adjust its cursor
  * position to keep the same Visual area.
  */
@@ -5039,10 +5040,15 @@ win_goto(win_T *wp)
     }
 
     if (wp->w_buffer != curbuf)
+	// careful: triggers ModeChanged autocommand
 	reset_VIsual_and_resel();
     else if (VIsual_active)
 	wp->w_cursor = curwin->w_cursor;
 
+    // autocommand may have made wp invalid
+    if (!win_valid(wp))
+	return;
+
 #ifdef FEAT_GUI
     need_mouse_correct = TRUE;
 #endif