From 610b4b0dbaedd3099ab76acf678e9cc845d99a76 Mon Sep 17 00:00:00 2001 From: stratakis Date: Mon, 25 Feb 2019 22:04:09 +0100 Subject: [PATCH] [3.5] bpo-34623: Use XML_SetHashSalt in _elementtree (#9933) * bpo-34623: Use XML_SetHashSalt in _elementtree (GH-9146) The C accelerated _elementtree module now initializes hash randomization salt from _Py_HashSecret instead of libexpat's default CPRNG. Signed-off-by: Christian Heimes https://bugs.python.org/issue34623 (cherry picked from commit cb5778f00ce48631c7140f33ba242496aaf7102b) Co-authored-by: Christian Heimes CVE: CVE-2018-14647 Upstream-Status: Backport [https://github.com/python/cpython/commit/41b48e71ac8a71f56694b548f118bd20ce203410] Signed-off-by: Dan Tran --- Include/pyexpat.h | 4 +++- .../next/Security/2018-09-10-16-05-39.bpo-34623.Ua9jMv.rst | 2 ++ Modules/_elementtree.c | 5 +++++ Modules/pyexpat.c | 5 +++++ 4 files changed, 15 insertions(+), 1 deletion(-) create mode 100644 Misc/NEWS.d/next/Security/2018-09-10-16-05-39.bpo-34623.Ua9jMv.rst diff --git a/Include/pyexpat.h b/Include/pyexpat.h index 44259bf6d7..07020b5dc9 100644 --- a/Include/pyexpat.h +++ b/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 a/Misc/NEWS.d/next/Security/2018-09-10-16-05-39.bpo-34623.Ua9jMv.rst b/Misc/NEWS.d/next/Security/2018-09-10-16-05-39.bpo-34623.Ua9jMv.rst new file mode 100644 index 0000000000..cbaa4b7506 --- /dev/null +++ b/Misc/NEWS.d/next/Security/2018-09-10-16-05-39.bpo-34623.Ua9jMv.rst @@ -0,0 +1,2 @@ +CVE-2018-14647: The C accelerated _elementtree module now initializes hash +randomization salt from _Py_HashSecret instead of libexpat's default CSPRNG. diff --git a/Modules/_elementtree.c b/Modules/_elementtree.c index 5dba9f70a9..90c6daf64a 100644 --- a/Modules/_elementtree.c +++ b/Modules/_elementtree.c @@ -3282,6 +3282,11 @@ _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 a/Modules/pyexpat.c b/Modules/pyexpat.c index adc9b6cde8..948ab1b703 100644 --- a/Modules/pyexpat.c +++ b/Modules/pyexpat.c @@ -1882,6 +1882,11 @@ 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); -- 2.22.0.vfs.1.1.57.gbaf16c8