gnu: python: Fix CVE-2018-14647.

* gnu/packages/patches/python-CVE-2018-14647.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.
* gnu/packages/python.scm (python-3/fixed): New variable.
(python-3.6)[replacement]: New field.
(python-minimal, python-debug, wrap-python3): Use PACKAGE/INHERIT instead of
standard inheritance.

gnu/local.mk

@@ -1076,6 +1076,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/python-3-deterministic-build-info.patch	\
   %D%/packages/patches/python-3-search-paths.patch		\
   %D%/packages/patches/python-3-fix-tests.patch			\
+  %D%/packages/patches/python-CVE-2018-14647.patch		\
   %D%/packages/patches/python-axolotl-AES-fix.patch		\
   %D%/packages/patches/python-cairocffi-dlopen-path.patch	\
   %D%/packages/patches/python-fix-tests.patch			\

gnu/packages/patches/python-CVE-2018-14647.patch

@@ -0,0 +1,61 @@
+Fix CVE-2018-14647:
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-14647
+https://bugs.python.org/issue34623
+
+Taken from upstream:
+https://github.com/python/cpython/commit/f7666e828cc3d5873136473ea36ba2013d624fa1
+
+diff --git Include/pyexpat.h Include/pyexpat.h
+index 44259bf6d7..07020b5dc9 100644
+--- Include/pyexpat.h
++++ Include/pyexpat.h
+@@ -3,7 +3,7 @@
+ 
+ /* note: you must import expat.h before importing this module! */
+ 
+-#define PyExpat_CAPI_MAGIC  "pyexpat.expat_CAPI 1.0"
++#define PyExpat_CAPI_MAGIC  "pyexpat.expat_CAPI 1.1"
+ #define PyExpat_CAPSULE_NAME "pyexpat.expat_CAPI"
+ 
+ struct PyExpat_CAPI
+@@ -48,6 +48,8 @@ struct PyExpat_CAPI
+     enum XML_Status (*SetEncoding)(XML_Parser parser, const XML_Char *encoding);
+     int (*DefaultUnknownEncodingHandler)(
+         void *encodingHandlerData, const XML_Char *name, XML_Encoding *info);
++    /* might be none for expat < 2.1.0 */
++    int (*SetHashSalt)(XML_Parser parser, unsigned long hash_salt);
+     /* always add new stuff to the end! */
+ };
+ 
+diff --git Modules/_elementtree.c Modules/_elementtree.c
+index 707ab2912b..53f05f937f 100644
+--- Modules/_elementtree.c
++++ Modules/_elementtree.c
+@@ -3261,6 +3261,11 @@ _elementtree_XMLParser___init___impl(XMLParserObject *self, PyObject *html,
+         PyErr_NoMemory();
+         return -1;
+     }
++    /* expat < 2.1.0 has no XML_SetHashSalt() */
++    if (EXPAT(SetHashSalt) != NULL) {
++        EXPAT(SetHashSalt)(self->parser,
++                           (unsigned long)_Py_HashSecret.expat.hashsalt);
++    }
+ 
+     if (target) {
+         Py_INCREF(target);
+diff --git Modules/pyexpat.c Modules/pyexpat.c
+index 47c3e86c20..aa21d93c11 100644
+--- Modules/pyexpat.c
++++ Modules/pyexpat.c
+@@ -1887,6 +1887,11 @@ MODULE_INITFUNC(void)
+     capi.SetStartDoctypeDeclHandler = XML_SetStartDoctypeDeclHandler;
+     capi.SetEncoding = XML_SetEncoding;
+     capi.DefaultUnknownEncodingHandler = PyUnknownEncodingHandler;
++#if XML_COMBINED_VERSION >= 20100
++    capi.SetHashSalt = XML_SetHashSalt;
++#else
++    capi.SetHashSalt = NULL;
++#endif
+ 
+     /* export using capsule */
+     capi_object = PyCapsule_New(&capi, PyExpat_CAPSULE_NAME, NULL);

gnu/packages/python.scm

@@ -357,6 +357,7 @@ (define-public python-3.6
   (package (inherit python-2)
     (name "python")
     (version "3.6.5")
+    (replacement python-3/fixed)
     (source (origin
               (method url-fetch)
               (uri (string-append "https://www.python.org/ftp/python/"
@@ -456,6 +457,24 @@ (define-public python-3.6
 ;; Current 3.x version.
 (define-public python-3 python-3.6)
 
+(define python-3/fixed
+  (package
+    (inherit python-3)
+    (source (origin
+              (inherit (package-source python-3))
+              (patches (append (origin-patches (package-source python-3))
+                               (search-patches "python-CVE-2018-14647.patch")))))
+    (arguments
+     (substitute-keyword-arguments (package-arguments python-3)
+       ((#:phases phases)
+        `(modify-phases ,phases
+           (add-after 'unpack 'delete-broken-test
+             (lambda _
+               ;; Delete test which fails on recent kernels:
+               ;; <https://bugs.python.org/issue34587>.
+               (delete-file "Lib/test/test_socket.py")
+               #t))))))))
+
 ;; Current major version.
 (define-public python python-3)
 
@@ -474,7 +493,7 @@ (define-public python2-minimal
               ("zlib" ,zlib)))))
 
 (define-public python-minimal
-  (package (inherit python)
+  (package/inherit python
     (name "python-minimal")
     (outputs '("out"))
 
@@ -486,8 +505,7 @@ (define-public python-minimal
               ("zlib" ,zlib)))))
 
 (define-public python-debug
-  (package
-    (inherit python)
+  (package/inherit python
     (name "python-debug")
     (outputs '("out" "debug"))
     (build-system gnu-build-system)
@@ -506,7 +524,7 @@ (define-public python-debug
 (define* (wrap-python3 python
                        #:optional
                        (name (string-append (package-name python) "-wrapper")))
-  (package (inherit python)
+  (package/inherit python
     (name name)
     (source #f)
     (build-system trivial-build-system)