From 5c1399c30901b98ee9eb0b83be2847eb74b9e80d Mon Sep 17 00:00:00 2001
From: matt335672 <30179339+matt335672@users.noreply.github.com>
Date: Wed, 7 Dec 2022 10:49:06 +0000
Subject: [PATCH 9/9] CVE-2022-23493

Check chansrv channel ID on a channel close

Prevent OOB read if an invalid channel ID is sent.
---
 xrdp/xrdp_mm.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/xrdp/xrdp_mm.c b/xrdp/xrdp_mm.c
index b59345d7..c27c2341 100644
--- a/xrdp/xrdp_mm.c
+++ b/xrdp/xrdp_mm.c
@@ -1447,6 +1447,12 @@ xrdp_mm_trans_process_drdynvc_channel_close(struct xrdp_mm *self,
         return 1;
     }
     in_uint32_le(s, chansrv_chan_id);
+    if (chansrv_chan_id < 0 || chansrv_chan_id > 255)
+    {
+        LOG(LOG_LEVEL_ERROR, "Attempting to close invalid chansrv channel %d",
+            chansrv_chan_id);
+        return 1;
+    }
     chan_id = self->cs2xr_cid_map[chansrv_chan_id];
     /* close dynamic channel */
     error = libxrdp_drdynvc_close(self->wm->session, chan_id);
-- 
2.39.0