Fix for CVE-2023-1393

Resolves: rhbz#2180299

0001-composite-Fix-use-after-free-of-the-COW.patch

@@ -0,0 +1,42 @@
+From 26ef545b3502f61ca722a7a3373507e88ef64110 Mon Sep 17 00:00:00 2001
+From: Olivier Fourdan <ofourdan@redhat.com>
+Date: Mon, 13 Mar 2023 11:08:47 +0100
+Subject: [PATCH xserver] composite: Fix use-after-free of the COW
+
+ZDI-CAN-19866/CVE-2023-1393
+
+If a client explicitly destroys the compositor overlay window (aka COW),
+we would leave a dangling pointer to that window in the CompScreen
+structure, which will trigger a use-after-free later.
+
+Make sure to clear the CompScreen pointer to the COW when the latter gets
+destroyed explicitly by the client.
+
+This vulnerability was discovered by:
+Jan-Niklas Sohn working with Trend Micro Zero Day Initiative
+
+Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
+Reviewed-by: Adam Jackson <ajax@redhat.com>
+---
+ composite/compwindow.c | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/composite/compwindow.c b/composite/compwindow.c
+index 4e2494b86..b30da589e 100644
+--- a/composite/compwindow.c
++++ b/composite/compwindow.c
+@@ -620,6 +620,11 @@ compDestroyWindow(WindowPtr pWin)
+     ret = (*pScreen->DestroyWindow) (pWin);
+     cs->DestroyWindow = pScreen->DestroyWindow;
+     pScreen->DestroyWindow = compDestroyWindow;
++
++    /* Did we just destroy the overlay window? */
++    if (pWin == cs->pOverlayWin)
++        cs->pOverlayWin = NULL;
++
+ /*    compCheckTree (pWin->drawable.pScreen); can't check -- tree isn't good*/
+     return ret;
+ }
+-- 
+2.40.0
+

xorg-x11-server-Xwayland.spec

@@ -9,7 +9,7 @@
 Summary:   Xwayland
 Name:      xorg-x11-server-Xwayland
 Version:   21.1.3
-Release:   7%{?gitdate:.%{gitdate}git%{shortcommit}}%{?dist}
+Release:   8%{?gitdate:.%{gitdate}git%{shortcommit}}%{?dist}
 
 URL:       http://www.x.org
 %if 0%{?gitdate}
@@ -57,6 +57,8 @@ Patch10016: 0007-xkb-reset-the-radio_groups-pointer-to-NULL-after-fre.patch
 Patch10017: 0008-Xext-fix-invalid-event-type-mask-in-XTestSwapFakeInp.patch
 # CVE-2023-0494
 Patch10018: 0001-Xi-fix-potential-use-after-free-in-DeepCopyPointerCl.patch
+# CVE-2023-1393
+Patch10019: 0001-composite-Fix-use-after-free-of-the-COW.patch
 
 License:   MIT
 
@@ -163,6 +165,9 @@ rm -Rf $RPM_BUILD_ROOT%{_localstatedir}/lib/xkb
 %{_libdir}/pkgconfig/xwayland.pc
 
 %changelog
+* Fri Mar 31 2023 Olivier Fourdan <ofourdan@redhat.com> - 21.1.3-8
+- Fix CVE-2023-1393 (#2180299)
+
 * Tue Feb  7 2023 Olivier Fourdan <ofourdan@redhat.com> - 21.1.3-7
 - Fix CVE-2023-0494 (#2166974)