gnu: QEMU: Fix CVE-2018-16847 and CVE-2018-16867.

* gnu/packages/patches/qemu-CVE-2018-16847.patch,
gnu/packages/patches/qemu-CVE-2018-16867.patch: New files.
* gnu/local.mk (dist_patch_DATA): Add them.
* gnu/packages/virtualization.scm (qemu)[source]: Use them.

gnu/packages/patches/qemu-CVE-2018-16867.patch

@@ -0,0 +1,49 @@
+Fix CVE-2018-16867:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-16867
+https://seclists.org/oss-sec/2018/q4/202
+
+Patch copied from upstream source repository:
+
+https://git.qemu.org/?p=qemu.git;a=commitdiff;h=c52d46e041b42bb1ee6f692e00a0abe37a9659f6
+
+From c52d46e041b42bb1ee6f692e00a0abe37a9659f6 Mon Sep 17 00:00:00 2001
+From: Gerd Hoffmann <kraxel@redhat.com>
+Date: Mon, 3 Dec 2018 11:10:45 +0100
+Subject: [PATCH] usb-mtp: outlaw slashes in filenames
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Slash is unix directory separator, so they are not allowed in filenames.
+Note this also stops the classic escape via "../".
+
+Fixes: CVE-2018-16867
+Reported-by: Michael Hanselmann <public@hansmi.ch>
+Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
+Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
+Message-id: 20181203101045.27976-3-kraxel@redhat.com
+---
+ hw/usb/dev-mtp.c | 6 ++++++
+ 1 file changed, 6 insertions(+)
+
+diff --git a/hw/usb/dev-mtp.c b/hw/usb/dev-mtp.c
+index 0f6a9702ef1..100b7171f4e 100644
+--- a/hw/usb/dev-mtp.c
++++ b/hw/usb/dev-mtp.c
+@@ -1719,6 +1719,12 @@ static void usb_mtp_write_metadata(MTPState *s)
+ 
+     filename = utf16_to_str(dataset->length, dataset->filename);
+ 
++    if (strchr(filename, '/')) {
++        usb_mtp_queue_result(s, RES_PARAMETER_NOT_SUPPORTED, d->trans,
++                             0, 0, 0, 0);
++        return;
++    }
++
+     o = usb_mtp_object_lookup_name(p, filename, dataset->length);
+     if (o != NULL) {
+         next_handle = o->handle;
+-- 
+2.19.2
+