python: CVE-2014-4616

Fix for _json module arbitrary process memory read vulnerability

http://bugs.python.org/issue21529

Python 2 and 3 are susceptible to arbitrary process memory reading
by a user or adversary due to a bug in the _json module caused by
insufficient bounds checking.

The sole prerequisites of this attack are that the attacker is able to control
or influence the two parameters of the default scanstring function: the string
to be decoded and the index. The bug is caused by allowing the user to supply
a negative index value. The index value is then used directly as an index to
an array in the C code; internally the address of the array and its index are
added to each other in order to yield the address of the value that is desired.
However, by supplying a negative index value and adding this to the address of
the array, the processor's register value wraps around and the calculated value
will point to a position in memory which isn't within the bounds of the
supplied string, causing the function to access other parts of the process
memory.

Signed-off-by: Benjamin Peterson <benjamin@python.org> Applied to
python-native recipe in order to fix the above mentioned vulnerability.

Upstream-Status: Backport

Signed-off-by: Daniel BORNAZ <daniel.bornaz@enea.com>
Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>

2 files changed, 28 insertions, 0 deletions

diff --git a/meta/recipes-devtools/python/python/json-flaw-CVE-2014-4616.patch b/meta/recipes-devtools/python/python/json-flaw-CVE-2014-4616.patch
new file mode 100644
index 0000000000..e9a6cca017
--- /dev/null
+++ b/meta/recipes-devtools/python/python/json-flaw-CVE-2014-4616.patch
@@ -0,0 +1,27 @@
+
+python: fix _json module arbitrary process memory read vulnerability
+
+Upstream-Status: submitted
+
+Signed-off-by: Daniel BORNAZ <daniel.bornaz@enea.com>
+
+--- a/Modules/_json.c   2014-07-15 15:37:17.151046356 +0200
++++ b/Modules/_json.c   2014-07-15 15:38:37.335605042 +0200
+@@ -1491,7 +1491,7 @@ scan_once_str(PyScannerObject *s, PyObje
+     PyObject *res;
+     char *str = PyString_AS_STRING(pystr);
+     Py_ssize_t length = PyString_GET_SIZE(pystr);
+-    if (idx >= length) {
++    if ( idx < 0 || idx >= length) {
+         PyErr_SetNone(PyExc_StopIteration);
+         return NULL;
+     }
+@@ -1578,7 +1578,7 @@ scan_once_unicode(PyScannerObject *s, Py
+     PyObject *res;
+     Py_UNICODE *str = PyUnicode_AS_UNICODE(pystr);
+     Py_ssize_t length = PyUnicode_GET_SIZE(pystr);
+-    if (idx >= length) {
++    if ( idx < 0 || idx >= length) {
+         PyErr_SetNone(PyExc_StopIteration);
+         return NULL;
+     }
diff --git a/meta/recipes-devtools/python/python_2.7.3.bb b/meta/recipes-devtools/python/python_2.7.3.bb
index 0d641720f1..bbe16eb5d2 100644
--- a/meta/recipes-devtools/python/python_2.7.3.bb
+++ b/meta/recipes-devtools/python/python_2.7.3.bb
@@ -36,6 +36,7 @@ SRC_URI += "\
   file://python-2.7.3-CVE-2013-1752-smtplib-fix.patch \
   file://python-fix-build-error-with-Readline-6.3.patch \
   file://python-2.7.3-CVE-2014-1912.patch \
+  file://json-flaw-CVE-2014-4616.patch \
 "
 
 S = "${WORKDIR}/Python-${PV}"