From 2fda7c57e7ebe210cf5e2bb051a0a9271f85e80a Mon Sep 17 00:00:00 2001
From: Matthieu Herrb <matthieu@herrb.eu>
Date: Mon, 22 Oct 2018 14:33:25 -0400
Subject: [PATCH xserver] Disable -logfile and -modulepath when running with
 elevated privileges

An unprivileged user was able to overwrite arbitrary files
in directories in which it is able to chdir, potentially
leading to privilege elevation.

CVE-2018-14665

An unprivileded user was able to load arbitrary modules
from user controlled directories, leading to privilege
elevation.

CVE-2018-XXXXX

Issues reported by Narendra Shinde

Signed-off-by: Matthieu Herrb <matthieu@herrb.eu>
Reviewed-by: Alan Coopersmith <alan.coopersmith@oracle.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 6c25eda739..0f57efa863 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;
--
2.19.0
