curl: backport fix for CVE-2019-15601

On Windows, refuse paths that start with \\ ... as that might cause an
unexpected SMB connection to a given host name.

Ref: PR#2730
Ref: https://curl.haxx.se/docs/CVE-2019-15601.html
Suggested-by: Jerome Benoit <jerome.benoit@sap.com>
Signed-off-by: Petr Štetiar <ynezz@true.cz>

package/network/utils/curl/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=curl
 PKG_VERSION:=7.66.0
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.xz
 PKG_SOURCE_URL:=https://dl.uxnr.de/mirror/curl/ \

package/network/utils/curl/patches/100-file-on-Windows-refuse-paths-that-start-with.patch

@@ -0,0 +1,44 @@
+From 1b71bc532bde8621fd3260843f8197182a467ff2 Mon Sep 17 00:00:00 2001
+From: Daniel Stenberg <daniel@haxx.se>
+Date: Thu, 7 Nov 2019 10:13:01 +0100
+Subject: [PATCH] file: on Windows, refuse paths that start with \\
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+... as that might cause an unexpected SMB connection to a given host
+name.
+
+Reported-by: Fernando Muñoz
+CVE-2019-15601
+Bug: https://curl.haxx.se/docs/CVE-2019-15601.html
+
+Signed-off-by: Petr Štetiar <ynezz@true.cz>
+---
+ lib/file.c | 6 ++++--
+ 1 file changed, 4 insertions(+), 2 deletions(-)
+
+diff --git a/lib/file.c b/lib/file.c
+index d349cd9241cd..166931d7f1ba 100644
+--- a/lib/file.c
++++ b/lib/file.c
+@@ -136,7 +136,7 @@ static CURLcode file_connect(struct connectdata *conn, bool *done)
+   struct Curl_easy *data = conn->data;
+   char *real_path;
+   struct FILEPROTO *file = data->req.protop;
+-  int fd;
++  int fd = -1;
+ #ifdef DOS_FILESYSTEM
+   size_t i;
+   char *actual_path;
+@@ -181,7 +181,9 @@ static CURLcode file_connect(struct connectdata *conn, bool *done)
+       return CURLE_URL_MALFORMAT;
+     }
+ 
+-  fd = open_readonly(actual_path, O_RDONLY|O_BINARY);
++  if(strncmp("\\\\", actual_path, 2))
++    /* refuse to open path that starts with two backslashes */
++    fd = open_readonly(actual_path, O_RDONLY|O_BINARY);
+   file->path = actual_path;
+ #else
+   if(memchr(real_path, 0, real_path_len)) {