From 25aabc2b8ee1e19ced6f4da9d866cf9378fc4c5a Mon Sep 17 00:00:00 2001
From: Christian Brabandt <cb@256bit.org>
Date: Tue, 14 Nov 2023 19:31:34 +0100
Subject: [PATCH] patch 9.0.2106: [security]: Use-after-free in win_close()

Problem:  [security]: Use-after-free in win_close()
Solution: Check window is valid, before accessing it

If the current window structure is no longer valid (because a previous
autocommand has already freed this window), fail and return before
attempting to set win->w_closing variable.

Add a test to trigger ASAN in CI

Signed-off-by: Christian Brabandt <cb@256bit.org>
---
 src/window.c               |   2 ++
 1 files changed, 2 insertions(+)

diff --git a/src/window.c b/src/window.c
index f77ede330d304..55ce31c886437 100644
--- a/src/window.c
+++ b/src/window.c
@@ -2682,6 +2682,8 @@ win_close(win_T *win, int free_buf)
 	    reset_VIsual_and_resel();	// stop Visual mode
 
 	    other_buffer = TRUE;
+	    if (!win_valid(win))
+		return FAIL;
 	    win->w_closing = TRUE;
 	    apply_autocmds(EVENT_BUFLEAVE, NULL, NULL, FALSE, curbuf);
 	    if (!win_valid(win))