From: Christian Brabandt <cb@256bit.org>
Date: Tue, 28 Nov 2023 21:03:48 +0000 (+0100)
Subject: patch 9.0.2140: [security]: use-after-free in win-enter
X-Git-Tag: v9.0.2140^0
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=eec0c2b3a4cfab93dd8d4adaa60638d47a2bbc8a;p=thirdparty%2Fvim.git

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 0000000000..73f53b575b
Binary files /dev/null and b/src/testdir/crash/poc_win_enter_ext differ
diff --git a/src/testdir/test_crash.vim b/src/testdir/test_crash.vim
index b093b053c5..11c5f4e014 100644
--- 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
index 3fc23c17e5..e32e5c006d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2140,
 /**/
     2139,
 /**/
diff --git a/src/window.c b/src/window.c
index 0f4363b942..be010dc7fd 100644
--- 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