xserver-xorg: fix CVE-2021-3472

Insufficient checks on the lengths of the XInput extension
ChangeFeedbackControl request can lead to out of bounds memory accesses
in the X server.

References:
https://nvd.nist.gov/vuln/detail/CVE-2021-3472

Upstream patches:
https://gitlab.freedesktop.org/xorg/xserver/-/commit/7aaf54a1884f71dc363f0b884e57bcb67407a6cd

(From OE-Core rev: 6fec5fea942ce88e33e5cf4c2102d69ce25e7180)

Signed-off-by: Stefan Ghinea <stefan.ghinea@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 44 insertions, 0 deletions

diff --git a/meta/recipes-graphics/xorg-xserver/xserver-xorg/CVE-2021-3472.patch b/meta/recipes-graphics/xorg-xserver/xserver-xorg/CVE-2021-3472.patch
new file mode 100644
index 0000000000..5480f71871
--- /dev/null
+++ b/meta/recipes-graphics/xorg-xserver/xserver-xorg/CVE-2021-3472.patch
@@ -0,0 +1,43 @@
+From 7aaf54a1884f71dc363f0b884e57bcb67407a6cd Mon Sep 17 00:00:00 2001
+From: Matthieu Herrb <matthieu@herrb.eu>
+Date: Sun, 21 Mar 2021 18:38:57 +0100
+Subject: [PATCH] Fix XChangeFeedbackControl() request underflow
+
+CVE-2021-3472 / ZDI-CAN-1259
+
+This vulnerability was discovered by:
+Jan-Niklas Sohn working with Trend Micro Zero Day Initiative
+
+Signed-off-by: Matthieu Herrb <matthieu@herrb.eu>
+
+Upstream-Status: Backport
+CVE: CVE-2021-3472
+
+Reference to upstream patch:
+[https://gitlab.freedesktop.org/xorg/xserver/-/commit/7aaf54a1884f71dc363f0b884e57bcb67407a6cd]
+
+Signed-off-by: Stefan Ghinea <stefan.ghinea@windriver.com>
+---
+ Xi/chgfctl.c | 5 ++++-
+ 1 file changed, 4 insertions(+), 1 deletion(-)
+
+diff --git a/Xi/chgfctl.c b/Xi/chgfctl.c
+index 1de4da9..7a597e4 100644
+--- a/Xi/chgfctl.c
++++ b/Xi/chgfctl.c
+@@ -464,8 +464,11 @@ ProcXChangeFeedbackControl(ClientPtr client)
+         break;
+     case StringFeedbackClass:
+     {
+-        xStringFeedbackCtl *f = ((xStringFeedbackCtl *) &stuff[1]);
++        xStringFeedbackCtl *f;
+ 
++        REQUEST_AT_LEAST_EXTRA_SIZE(xChangeFeedbackControlReq,
++                                    sizeof(xStringFeedbackCtl));
++        f = ((xStringFeedbackCtl *) &stuff[1]);
+         if (client->swapped) {
+             if (len < bytes_to_int32(sizeof(xStringFeedbackCtl)))
+                 return BadLength;
+-- 
+2.17.1
+
diff --git a/meta/recipes-graphics/xorg-xserver/xserver-xorg_1.20.10.bb b/meta/recipes-graphics/xorg-xserver/xserver-xorg_1.20.10.bb
index 5c6dbac4d7..755a762a73 100644
--- a/meta/recipes-graphics/xorg-xserver/xserver-xorg_1.20.10.bb
+++ b/meta/recipes-graphics/xorg-xserver/xserver-xorg_1.20.10.bb
@@ -7,6 +7,7 @@ SRC_URI += "file://0001-xf86pciBus.c-use-Intel-ddx-only-for-pre-gen4-hardwar.pat
            file://0001-drmmode_display.c-add-missing-mi.h-include.patch \
            file://0001-Avoid-duplicate-definitions-of-IOPortBase.patch \
            file://0001-Fix-segfault-on-probing-a-non-PCI-platform-device-on.patch \
+           file://CVE-2021-3472.patch \
            "
 SRC_URI[sha256sum] = "977420c082450dc808de301ef56af4856d653eea71519a973c3490a780cb7c99"