gnu: OpenSSH: Fix CVE-2018-20685.

* gnu/packages/patches/openssh-CVE-2018-20685.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/ssh.scm (openssh)[source]: Use it.

gnu/local.mk

@@ -1088,6 +1088,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/openldap-CVE-2017-9287.patch		\
   %D%/packages/patches/openocd-nrf52.patch			\
   %D%/packages/patches/opensmtpd-fix-crash.patch		\
+  %D%/packages/patches/openssh-CVE-2018-20685.patch		\
   %D%/packages/patches/openssl-runpath.patch			\
   %D%/packages/patches/openssl-1.1-c-rehash-in.patch		\
   %D%/packages/patches/openssl-c-rehash-in.patch		\

gnu/packages/patches/openssh-CVE-2018-20685.patch

@@ -0,0 +1,44 @@
+Fix CVE-2018-20685:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-20685
+
+Patch copied from upstream source repository:
+
+https://github.com/openssh/openssh-portable/commit/6010c0303a422a9c5fa8860c061bf7105eb7f8b2
+
+From 6010c0303a422a9c5fa8860c061bf7105eb7f8b2 Mon Sep 17 00:00:00 2001
+From: "djm@openbsd.org" <djm@openbsd.org>
+Date: Fri, 16 Nov 2018 03:03:10 +0000
+Subject: [PATCH] upstream: disallow empty incoming filename or ones that refer
+ to the
+
+current directory; based on report/patch from Harry Sintonen
+
+OpenBSD-Commit-ID: f27651b30eaee2df49540ab68d030865c04f6de9
+---
+ scp.c | 5 +++--
+ 1 file changed, 3 insertions(+), 2 deletions(-)
+
+diff --git a/scp.c b/scp.c
+index 60682c68..4f3fdcd3 100644
+--- a/scp.c
++++ b/scp.c
+#@@ -1,4 +1,4 @@
+#-/* $OpenBSD: scp.c,v 1.197 2018/06/01 04:31:48 dtucker Exp $ */
+#+/* $OpenBSD: scp.c,v 1.198 2018/11/16 03:03:10 djm Exp $ */
+# /*
+#  * scp - secure remote copy.  This is basically patched BSD rcp which
+#  * uses ssh to do the data transfer (instead of using rcmd).
+@@ -1106,7 +1106,8 @@ sink(int argc, char **argv)
+ 			SCREWUP("size out of range");
+ 		size = (off_t)ull;
+ 
+-		if ((strchr(cp, '/') != NULL) || (strcmp(cp, "..") == 0)) {
++		if (*cp == '\0' || strchr(cp, '/') != NULL ||
++		    strcmp(cp, ".") == 0 || strcmp(cp, "..") == 0) {
+ 			run_err("error: unexpected filename: %s", cp);
+ 			exit(1);
+ 		}
+-- 
+2.20.1
+

gnu/packages/ssh.scm

@@ -149,6 +149,7 @@ (define-public openssh
              (method url-fetch)
              (uri (string-append "mirror://openbsd/OpenSSH/portable/"
                                  name "-" version ".tar.gz"))
+             (patches (search-patches "openssh-CVE-2018-20685.patch"))
              (sha256
               (base32
                "1b8sy6v0b8v4ggmknwcqx3y1rjcpsll0f1f8f4vyv11x4ni3njvb"))))