xserver-xorg: fix CVE-2018-14665

Incorrect command-line parameter validation in the Xorg X server can lead to
privilege elevation and/or arbitrary files overwrite, when the X server is
running with elevated privileges (ie when Xorg is installed with the setuid bit
set and started by a non-root user). The -modulepath argument can be used to
specify an insecure path to modules that are going to be loaded in the X server,
allowing to execute unprivileged code in the privileged process. The -logfile
argument can be used to overwrite arbitrary files in the file system, due to
incorrect checks in the parsing of the option.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 63 insertions, 0 deletions

diff --git a/meta/recipes-graphics/xorg-xserver/xserver-xorg/CVE-2018-14665.patch b/meta/recipes-graphics/xorg-xserver/xserver-xorg/CVE-2018-14665.patch
new file mode 100644
index 0000000000..7f6235b432
--- /dev/null
+++ b/meta/recipes-graphics/xorg-xserver/xserver-xorg/CVE-2018-14665.patch
@@ -0,0 +1,62 @@
+Incorrect command-line parameter validation in the Xorg X server can lead to
+privilege elevation and/or arbitrary files overwrite, when the X server is
+running with elevated privileges (ie when Xorg is installed with the setuid bit
+set and started by a non-root user). The -modulepath argument can be used to
+specify an insecure path to modules that are going to be loaded in the X server,
+allowing to execute unprivileged code in the privileged process. The -logfile
+argument can be used to overwrite arbitrary files in the file system, due to
+incorrect checks in the parsing of the option.
+
+CVE: CVE-2018-14665
+Upstream-Status: Backport
+Signed-off-by: Ross Burton <ross.burton@intel.com>
+
+From 50c0cf885a6e91c0ea71fb49fa8f1b7c86fe330e Mon Sep 17 00:00:00 2001
+From: Matthieu Herrb <matthieu@herrb.eu>
+Date: Tue, 23 Oct 2018 21:29:08 +0200
+Subject: [PATCH] Disable -logfile and -modulepath when running with elevated
+ privileges
+
+Could cause privilege elevation and/or arbitrary files overwrite, when
+the X server is running with elevated privileges (ie when Xorg is
+installed with the setuid bit set and started by a non-root user).
+
+CVE-2018-14665
+
+Issue reported by Narendra Shinde and Red Hat.
+
+Signed-off-by: Matthieu Herrb <matthieu@herrb.eu>
+Reviewed-by: Alan Coopersmith <alan.coopersmith@oracle.com>
+Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
+Reviewed-by: Adam Jackson <ajax@redhat.com>
+---
+ hw/xfree86/common/xf86Init.c | 8 ++++++--
+ 1 file changed, 6 insertions(+), 2 deletions(-)
+
+diff --git a/hw/xfree86/common/xf86Init.c b/hw/xfree86/common/xf86Init.c
+index 6c25eda73..0f57efa86 100644
+--- a/hw/xfree86/common/xf86Init.c
++++ b/hw/xfree86/common/xf86Init.c
+@@ -935,14 +935,18 @@ ddxProcessArgument(int argc, char **argv, int i)
+     /* First the options that are not allowed with elevated privileges */
+     if (!strcmp(argv[i], "-modulepath")) {
+         CHECK_FOR_REQUIRED_ARGUMENT();
+-        xf86CheckPrivs(argv[i], argv[i + 1]);
++        if (xf86PrivsElevated())
++              FatalError("\nInvalid argument -modulepath "
++                "with elevated privileges\n");
+         xf86ModulePath = argv[i + 1];
+         xf86ModPathFrom = X_CMDLINE;
+         return 2;
+     }
+     if (!strcmp(argv[i], "-logfile")) {
+         CHECK_FOR_REQUIRED_ARGUMENT();
+-        xf86CheckPrivs(argv[i], argv[i + 1]);
++        if (xf86PrivsElevated())
++              FatalError("\nInvalid argument -logfile "
++                "with elevated privileges\n");
+         xf86LogFile = argv[i + 1];
+         xf86LogFileFrom = X_CMDLINE;
+         return 2;
+-- 
+2.18.1
diff --git a/meta/recipes-graphics/xorg-xserver/xserver-xorg_1.20.1.bb b/meta/recipes-graphics/xorg-xserver/xserver-xorg_1.20.1.bb
index cfdaf73175..9fd2e8d870 100644
--- a/meta/recipes-graphics/xorg-xserver/xserver-xorg_1.20.1.bb
+++ b/meta/recipes-graphics/xorg-xserver/xserver-xorg_1.20.1.bb
@@ -3,6 +3,7 @@ require xserver-xorg.inc
 SRC_URI += "file://musl-arm-inb-outb.patch \
             file://0001-xf86pciBus.c-use-Intel-ddx-only-for-pre-gen4-hardwar.patch \
             file://pkgconfig.patch \
+            file://CVE-2018-14665.patch \
             "
 SRC_URI[md5sum] = "e525846d1d0af5732ba835f2e2ec066d"
 SRC_URI[sha256sum] = "59c99fe86fe75b8164c6567bfc6e982aecc2e4a51e6fbac1b842d5d00549e918"