Author: Armin Rigo <[email protected]>
Branch:
Changeset: r2197:856cf4804a52
Date: 2015-06-30 09:16 +0200
http://bitbucket.org/cffi/cffi/changeset/856cf4804a52/
Log: Issue #209: check for dereferencing NULL pointers
diff --git a/c/_cffi_backend.c b/c/_cffi_backend.c
--- a/c/_cffi_backend.c
+++ b/c/_cffi_backend.c
@@ -1898,11 +1898,21 @@
return NULL;
if (cd->c_type->ct_flags & CT_POINTER) {
- if (CDataOwn_Check(cd) && i != 0) {
- PyErr_Format(PyExc_IndexError,
- "cdata '%s' can only be indexed by 0",
- cd->c_type->ct_name);
- return NULL;
+ if (CDataOwn_Check(cd)) {
+ if (i != 0) {
+ PyErr_Format(PyExc_IndexError,
+ "cdata '%s' can only be indexed by 0",
+ cd->c_type->ct_name);
+ return NULL;
+ }
+ }
+ else {
+ if (cd->c_data == NULL) {
+ PyErr_Format(PyExc_RuntimeError,
+ "cannot dereference null pointer from cdata '%s'",
+ cd->c_type->ct_name);
+ return NULL;
+ }
}
}
else if (cd->c_type->ct_flags & CT_ARRAY) {
diff --git a/c/test_c.py b/c/test_c.py
--- a/c/test_c.py
+++ b/c/test_c.py
@@ -2110,8 +2110,7 @@
p = cast(BVoidP, 123456)
py.test.raises(TypeError, "p[0]")
p = cast(BVoidP, 0)
- if 'PY_DOT_PY' in globals(): py.test.skip("NULL crashes early on py.py")
- py.test.raises(TypeError, "p[0]")
+ py.test.raises((TypeError, RuntimeError), "p[0]")
def test_iter():
BInt = new_primitive_type("int")
@@ -3344,6 +3343,15 @@
check(4 | 8, "CHB", "GTB")
check(4 | 16, "CHB", "ROB")
+def test_dereference_null_ptr():
+ BInt = new_primitive_type("int")
+ BIntPtr = new_pointer_type(BInt)
+ p = cast(BIntPtr, 0)
+ py.test.raises(RuntimeError, "p[0]")
+ py.test.raises(RuntimeError, "p[0] = 42")
+ py.test.raises(RuntimeError, "p[42]")
+ py.test.raises(RuntimeError, "p[42] = -1")
+
def test_version():
# this test is here mostly for PyPy
assert __version__ == "1.1.2"
diff --git a/doc/source/whatsnew.rst b/doc/source/whatsnew.rst
--- a/doc/source/whatsnew.rst
+++ b/doc/source/whatsnew.rst
@@ -30,6 +30,11 @@
dict---assuming that ``lib`` has got no symbol called precisely
``__dict__``. (In general, it is safer to use ``dir(lib)``.)
+* Issue #209: dereferencing NULL pointers now raises RuntimeError
+ instead of segfaulting. Meant as a debugging aid. The check is
+ only for NULL: if you dereference random or dead pointers you might
+ still get segfaults.
+
1.1.2
=====
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