From f9c435822c852659e3926502829f1b13ce6efc37 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 xserver 3/7] 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 68c362c628..066ba21fba 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 94ef5a0ec0..acce94b2c6 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);

-- 

2.38.1