xwayland: fix CVE-2022-49737

In X.Org X server 20.11 through 21.1.16, when a client application
uses easystroke for mouse gestures, the main thread modifies various
data structures used by the input thread without acquiring a lock,
aka a race condition. In particular, AttachDevice in dix/devices.c
does not acquire an input lock.

Reference:
https://nvd.nist.gov/vuln/detail/CVE-2022-49737

Upstream patch:
https://gitlab.freedesktop.org/xorg/xserver/-/commit/dc7cb45482cea6ccec22d117ca0b489500b4d0a0

(From OE-Core rev: 740ea9019cf5cf309c5a4ef380eac17d21078ac8)

Signed-off-by: Yogita Urade <yogita.urade@windriver.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

2 files changed, 91 insertions, 0 deletions

diff --git a/meta/recipes-graphics/xwayland/xwayland/CVE-2022-49737.patch b/meta/recipes-graphics/xwayland/xwayland/CVE-2022-49737.patch
new file mode 100644
index 0000000000..86c9f59f8c
--- /dev/null
+++ b/meta/recipes-graphics/xwayland/xwayland/CVE-2022-49737.patch
@@ -0,0 +1,90 @@
+From dc7cb45482cea6ccec22d117ca0b489500b4d0a0 Mon Sep 17 00:00:00 2001
+From: tholin <thomas.lindroth@gmail.com>
+Date: Tue, 4 Jan 2022 12:08:11 +0000
+Subject: [PATCH] dix: Hold input lock for AttachDevice()
+
+Fix the following race:
+
+Possible data race during read of size 8 at 0xA112510 by thread #6
+Locks held: 1, at address 0x366B40
+   at 0x14C8B9: GetMaster (devices.c:2691)
+   by 0x15CFC5: IsFloating (events.c:346)
+   by 0x2B9554: miPointerGetScreen (mipointer.c:527)
+   by 0x1A5136: xf86PostButtonEventM (xf86Xinput.c:1379)
+   by 0x1A52BD: xf86PostButtonEvent (xf86Xinput.c:1345)
+   by 0x485F45B: EvdevProcessEvent (in /usr/lib64/xorg/modules/input/evdev_drv.so)
+   by 0x485FDAC: EvdevReadInput (in /usr/lib64/xorg/modules/input/evdev_drv.so)
+   by 0x195427: xf86ReadInput (xf86Events.c:247)
+   by 0x2CC113: InputReady (inputthread.c:180)
+   by 0x2CE4EA: ospoll_wait (ospoll.c:657)
+   by 0x2CC077: InputThreadDoWork (inputthread.c:369)
+   by 0x484A336: mythread_wrapper (hg_intercepts.c:406)
+
+This conflicts with a previous write of size 8 by thread #1
+Locks held: none
+   at 0x14D2C6: AttachDevice (devices.c:2609)
+   by 0x15CF85: ReattachToOldMaster (events.c:1457)
+   by 0x1647DD: DeactivateKeyboardGrab (events.c:1700)
+   by 0x25D7F1: ProcXIUngrabDevice (xigrabdev.c:169)
+   by 0x2552AD: ProcIDispatch (extinit.c:398)
+   by 0x155291: Dispatch (dispatch.c:479)
+   by 0x158CBA: dix_main (main.c:276)
+   by 0x143A3D: main (stubmain.c:34)
+ Address 0xa112510 is 336 bytes inside a block of size 904 alloc'd
+   at 0x4846571: calloc (vg_replace_malloc.c:1328)
+   by 0x14A0B3: AddInputDevice (devices.c:260)
+   by 0x1A31A0: xf86ActivateDevice (xf86Xinput.c:365)
+   by 0x1A4549: xf86NewInputDevice (xf86Xinput.c:948)
+   by 0x1A4B44: NewInputDeviceRequest (xf86Xinput.c:1090)
+   by 0x1B81FE: device_added (udev.c:282)
+   by 0x1B8516: config_udev_init (udev.c:439)
+   by 0x1B7091: config_init (config.c:50)
+   by 0x197970: InitInput (xf86Init.c:814)
+   by 0x158C6B: dix_main (main.c:250)
+   by 0x143A3D: main (stubmain.c:34)
+ Block was alloc'd by thread #1
+
+The steps to trigger the race are:
+1. Main thread does cleanup at mipointer.c:360 setting the slave device's
+   miPointerPtr to null.
+2. Input thread use MIPOINTER in mipointer.c and get the slave's
+   miPointerPtr = null.
+3. Main thread updates dev->master at devices.c:2609.
+4. MIPOINTER would now return the master's miPointerPtr but the input
+   thread already got the slave's miPointerPtr in step 2 and segfaults by
+   null ptr deref.
+
+Closes: https://gitlab.freedesktop.org/xorg/xserver/-/issues/1260
+Signed-off-by: Thomas Lindroth <thomas.lindroth@gmail.com>
+
+CVE: CVE-2022-49737
+Upstream-Status: Backport [https://gitlab.freedesktop.org/xorg/xserver/-/commit/dc7cb45482cea6ccec22d117ca0b489500b4d0a0]
+
+Signed-off-by: Yogita Urade <yogita.urade@windriver.com>
+---
+ dix/devices.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+diff --git a/dix/devices.c b/dix/devices.c
+index 459f1ed..e5a6f02 100644
+--- a/dix/devices.c
++++ b/dix/devices.c
+@@ -2671,6 +2671,8 @@ AttachDevice(ClientPtr client, DeviceIntPtr dev, DeviceIntPtr master)
+     if (IsFloating(dev) && !master && dev->enabled)
+         return Success;
+
++    input_lock();
++
+     /* free the existing sprite. */
+     if (IsFloating(dev) && dev->spriteInfo->paired == dev) {
+         screen = miPointerGetScreen(dev);
+@@ -2711,6 +2713,7 @@ AttachDevice(ClientPtr client, DeviceIntPtr dev, DeviceIntPtr master)
+         RecalculateMasterButtons(master);
+     }
+
++    input_unlock();
+     /* XXX: in theory, the MD should change back to its old, original
+      * classes when the last SD is detached. Thanks to the XTEST devices,
+      * we'll always have an SD attached until the MD is removed.
+--
+2.40.0
diff --git a/meta/recipes-graphics/xwayland/xwayland_22.1.8.bb b/meta/recipes-graphics/xwayland/xwayland_22.1.8.bb
index 6affd80e22..8b1fc85aab 100644
--- a/meta/recipes-graphics/xwayland/xwayland_22.1.8.bb
+++ b/meta/recipes-graphics/xwayland/xwayland_22.1.8.bb
@@ -42,6 +42,7 @@ SRC_URI = "https://www.x.org/archive/individual/xserver/xwayland-${PV}.tar.xz \
            file://CVE-2025-26601-2.patch \
            file://CVE-2025-26601-3.patch \
            file://CVE-2025-26601-4.patch \
+           file://CVE-2022-49737.patch \
 "
 SRC_URI[sha256sum] = "d11eeee73290b88ea8da42a7d9350dedfaba856ce4ae44e58c045ad9ecaa2f73"