From 8f454b793e1f13c99872c15f0eed1d7f3b823fe8 Mon Sep 17 00:00:00 2001
From: Peter Hutterer <peter.hutterer@who-t.net>
Date: Tue, 29 Nov 2022 13:26:57 +1000
Subject: [PATCH] Xi: avoid integer truncation in length check of
 ProcXIChangeProperty

This fixes an OOB read and the resulting information disclosure.

Length calculation for the request was clipped to a 32-bit integer. With
the correct stuff->num_items value the expected request size was
truncated, passing the REQUEST_FIXED_SIZE check.

The server then proceeded with reading at least stuff->num_items bytes
(depending on stuff->format) from the request and stuffing whatever it
finds into the property. In the process it would also allocate at least
stuff->num_items bytes, i.e. 4GB.

The same bug exists in ProcChangeProperty and ProcXChangeDeviceProperty,
so let's fix that too.

CVE-2022-46344, ZDI-CAN 19405

This vulnerability was discovered by:
Jan-Niklas Sohn working with Trend Micro Zero Day Initiative

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Acked-by: Olivier Fourdan <ofourdan@redhat.com>
---
 Xi/xiproperty.c | 4 ++--
 dix/property.c  | 3 ++-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/Xi/xiproperty.c b/Xi/xiproperty.c
index 68c362c62..066ba21fb 100644
--- a/Xi/xiproperty.c
+++ b/Xi/xiproperty.c
@@ -890,7 +890,7 @@ ProcXChangeDeviceProperty(ClientPtr client)
     REQUEST(xChangeDevicePropertyReq);
     DeviceIntPtr dev;
     unsigned long len;
-    int totalSize;
+    uint64_t totalSize;
     int rc;
 
     REQUEST_AT_LEAST_SIZE(xChangeDevicePropertyReq);
@@ -1130,7 +1130,7 @@ ProcXIChangeProperty(ClientPtr client)
 {
     int rc;
     DeviceIntPtr dev;
-    int totalSize;
+    uint64_t totalSize;
     unsigned long len;
 
     REQUEST(xXIChangePropertyReq);
diff --git a/dix/property.c b/dix/property.c
index 94ef5a0ec..acce94b2c 100644
--- a/dix/property.c
+++ b/dix/property.c
@@ -205,7 +205,8 @@ ProcChangeProperty(ClientPtr client)
     WindowPtr pWin;
     char format, mode;
     unsigned long len;
-    int sizeInBytes, totalSize, err;
+    int sizeInBytes, err;
+    uint64_t totalSize;
 
     REQUEST(xChangePropertyReq);
 
-- 
GitLab
