xserver-xorg: backport fix for CVE-2023-1393

(From OE-Core rev: dc2c777cab0230fc54e078d20d872aaa9287a8b9)

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 7828f7026b4cd3ae97ebe5d849c09fabbc17272d)
Signed-off-by: Steve Sakoman <steve@sakoman.com>

2 files changed, 48 insertions, 1 deletions

diff --git a/meta/recipes-graphics/xorg-xserver/xserver-xorg/0001-composite-Fix-use-after-free-of-the-COW.patch b/meta/recipes-graphics/xorg-xserver/xserver-xorg/0001-composite-Fix-use-after-free-of-the-COW.patch
new file mode 100644
index 0000000000..fc426daba5
--- /dev/null
+++ b/meta/recipes-graphics/xorg-xserver/xserver-xorg/0001-composite-Fix-use-after-free-of-the-COW.patch
@@ -0,0 +1,46 @@
+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] 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>
+
+CVE: CVE-2023-1393
+Upstream-Status: Backport
+Signed-off-by: Ross Burton <ross.burton@arm.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;
+ }
+-- 
+2.34.1
+
diff --git a/meta/recipes-graphics/xorg-xserver/xserver-xorg_21.1.7.bb b/meta/recipes-graphics/xorg-xserver/xserver-xorg_21.1.7.bb
index 212c7d39c2..f0771cc86e 100644
--- a/meta/recipes-graphics/xorg-xserver/xserver-xorg_21.1.7.bb
+++ b/meta/recipes-graphics/xorg-xserver/xserver-xorg_21.1.7.bb
@@ -1,7 +1,8 @@
 require xserver-xorg.inc
 
 SRC_URI += "file://0001-xf86pciBus.c-use-Intel-ddx-only-for-pre-gen4-hardwar.patch \
-           file://0001-Avoid-duplicate-definitions-of-IOPortBase.patch \
+            file://0001-Avoid-duplicate-definitions-of-IOPortBase.patch \
+            file://0001-composite-Fix-use-after-free-of-the-COW.patch \
            "
 SRC_URI[sha256sum] = "d9c60b2dd0ec52326ca6ab20db0e490b1ff4f566f59ca742d6532e92795877bb"