scp: disallow empty incoming filename or "."

Closes: #919101

5 files changed, 39 insertions, 3 deletions

diff --git a/debian/.git-dpm b/debian/.git-dpm
index f6384e17d..10491782a 100644
--- a/debian/.git-dpm
+++ b/debian/.git-dpm
@@ -1,6 +1,6 @@
 # see git-dpm(1) from git-dpm package
-1d2a55436d4b556269f42ad5f7e16608b5a8ed74
-1d2a55436d4b556269f42ad5f7e16608b5a8ed74
+dee21e97428e69d30e2d15c71f3e7cc08bf8e4f8
+dee21e97428e69d30e2d15c71f3e7cc08bf8e4f8
 3d246f10429fc9a37b98eabef94fe8dc7c61002b
 3d246f10429fc9a37b98eabef94fe8dc7c61002b
 openssh_7.9p1.orig.tar.gz
diff --git a/debian/changelog b/debian/changelog
index aee8f7b88..864e7b689 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -4,6 +4,8 @@ openssh (1:7.9p1-5) UNRELEASED; urgency=medium
     only used by sshd (closes: #858050).
   * Drop obsolete alternate build-dependency on libssl1.0-dev (closes:
     #917342).
+  * CVE-2018-20685: Apply upstream scp patch to disallow empty incoming
+    filename or ones that refer to the current directory (closes: #919101).
 
  -- Colin Watson <cjwatson@debian.org>  Thu, 06 Dec 2018 18:16:30 +0000
 
diff --git a/debian/patches/scp-disallow-dot-or-empty-filename.patch b/debian/patches/scp-disallow-dot-or-empty-filename.patch
new file mode 100644
index 000000000..716f2ffa8
--- /dev/null
+++ b/debian/patches/scp-disallow-dot-or-empty-filename.patch
@@ -0,0 +1,32 @@
+From dee21e97428e69d30e2d15c71f3e7cc08bf8e4f8 Mon Sep 17 00:00:00 2001
+From: "djm@openbsd.org" <djm@openbsd.org>
+Date: Fri, 16 Nov 2018 03:03:10 +0000
+Subject: upstream: disallow empty incoming filename or ones that refer to the
+
+current directory; based on report/patch from Harry Sintonen
+
+OpenBSD-Commit-ID: f27651b30eaee2df49540ab68d030865c04f6de9
+
+Origin: upstream, https://anongit.mindrot.org/openssh.git/commit/?id=6010c0303a422a9c5fa8860c061bf7105eb7f8b2
+Bug-Debian: https://bugs.debian.org/919101
+Last-Update: 2019-01-12
+
+Patch-Name: scp-disallow-dot-or-empty-filename.patch
+---
+ scp.c | 3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+diff --git a/scp.c b/scp.c
+index ed2864250..7163d33dc 100644
+--- a/scp.c
++++ b/scp.c
+@@ -1114,7 +1114,8 @@ 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);
+                }
diff --git a/debian/patches/series b/debian/patches/series
index a248f086a..a6fc19449 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -24,3 +24,4 @@ restore-authorized_keys2.patch
 seccomp-s390-flock-ipc.patch
 seccomp-s390-ioctl-ep11-crypto.patch
 conch-old-privkey-format.patch
+scp-disallow-dot-or-empty-filename.patch
diff --git a/scp.c b/scp.c
index ed2864250..7163d33dc 100644
--- a/scp.c
+++ b/scp.c
@@ -1114,7 +1114,8 @@ 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);
                 }