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bpo-31746: Fixed Segfaults in the sqlite module when uninitialized. by lielfr · Pull Request #3946 · python/cpython · GitHub
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bpo-31746: Fixed Segfaults in the sqlite module when uninitialized. #3946

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bpo-31746: Fixed Segfaults in the sqlite module when uninitialized. #3946

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bbe3a0e
bpo-31746: Fixed Segfaults in the sqlite module when uninitialized.
lielfr Oct 10, 2017
b57a6af
Added regression tests, changed RuntimeError to ProgrammingError, and…
lielfr Oct 11, 2017
9955edf
Fixing typo, identation and tests according to reviews.
lielfr Oct 13, 2017
c0920c8
The first example code doesn't crash anymore.
lielfr Jun 3, 2019
77b2946
No more crashes from #31746
lielfr Jun 3, 2019
0fcd075
Fixed C whitespace error
lielfr Jun 3, 2019
d8b4dd6
Fixing the files according to the feedback in the PR
lielfr Apr 28, 2021
51e7a9f
Adding whitespace at the end of regression.py
lielfr Apr 28, 2021
84326a2
Fixing unnecessary extra whitespace in regression.py
lielfr Apr 28, 2021
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27 changes: 27 additions & 0 deletions Lib/sqlite3/test/regression.py
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Original file line number Diff line number Diff line change
Expand Up @@ -414,6 +414,33 @@ def test_return_empty_bytestring(self):
val = cur.fetchone()[0]
self.assertEqual(val, b'')

def test_uninitialized_isolation_level(self):
"""
Previously trying to get the isolation level of an uninitialized Connection
caused a segfault, now it should just return None.

@orenmn orenmn Oct 11, 2017

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Other getters raise a ProgrammingError when they are called on an uninitialized Connection object.
IMHO this should be the same here.

"""
conn = sqlite.Connection.__new__(sqlite.Connection)
with self.assertRaises(sqlite.ProgrammingError):
conn.isolation_level

def test_cursor_invalid_isolation_level(self):
"""
When trying to call conn.cursor() when conn is a Connection object that
was not initialized properly, it caused a segfault. Now it should raise
a ProgrammingError.
"""
conn = sqlite.Connection.__new__(sqlite.Connection)
self.assertRaises(ValueError, conn.__init__, '', isolation_level='invalid isolation level')
self.assertRaises(sqlite.ProgrammingError, conn.cursor)


def test_close_invalid_connection(self):
"""
Trying to call close() on a connection which was not initialized properly,
it caused a segfault. Now it should raise a ProgrammingError.
"""
conn = sqlite.Connection.__new__(sqlite.Connection)
self.assertRaises(sqlite.ProgrammingError, conn.close)

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def suite():
tests = [
Expand Down
31 changes: 31 additions & 0 deletions Modules/_sqlite/connection.c
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Original file line number Diff line number Diff line change
Expand Up @@ -118,11 +118,15 @@ pysqlite_connection_init(pysqlite_Connection *self, PyObject *args,
if (!isolation_level) {
isolation_level = PyUnicode_FromString("");
if (!isolation_level) {
PyErr_SetString(pysqlite_ProgrammingError, "Isolation level could not be set.");
return -1;
}
} else {
Py_INCREF(isolation_level);
}

self->initialized = 1;

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Py_CLEAR(self->isolation_level);
if (pysqlite_connection_set_isolation_level(self, isolation_level, NULL) < 0) {
Py_DECREF(isolation_level);
Expand Down Expand Up @@ -250,8 +254,19 @@ pysqlite_connection_dealloc(pysqlite_Connection *self)
*/
int pysqlite_connection_register_cursor(pysqlite_Connection* connection, PyObject* cursor)
{
if (!connection || !connection->cursors) {
PyErr_Format(pysqlite_ProgrammingError,
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"Base Connection.__init__ not called.");
goto error;
}
PyObject* weakref;

if (!connection->cursors) {
PyErr_SetString(pysqlite_ProgrammingError,
"Base Connection.__init__ not called.");
goto error;
}

weakref = PyWeakref_NewRef((PyObject*)cursor, NULL);
if (!weakref) {
goto error;
Expand Down Expand Up @@ -281,6 +296,11 @@ static PyObject *
pysqlite_connection_cursor_impl(pysqlite_Connection *self, PyObject *factory)
/*[clinic end generated code: output=562432a9e6af2aa1 input=4127345aa091b650]*/
{
if (self == NULL) {
return NULL;
}

static char *kwlist[] = {"factory", NULL};
Comment on lines +299 to +303

@erlend-aasland erlend-aasland Apr 30, 2021

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This is not needed if self->initialized is only set if pysqlite_connection_init was successful. Also, it looks like the rebase left some artifacts :)

PyObject* cursor;

if (!pysqlite_check_thread(self) || !pysqlite_check_connection(self)) {
Expand Down Expand Up @@ -323,6 +343,12 @@ pysqlite_connection_close_impl(pysqlite_Connection *self)
/*[clinic end generated code: output=a546a0da212c9b97 input=3d58064bbffaa3d3]*/
{
int rc;

if (!self->statements) {
PyErr_SetString(pysqlite_ProgrammingError,
"Base Connection.__init__ not called.");
return NULL;
}
Comment on lines +346 to +351

@erlend-aasland erlend-aasland Apr 30, 2021

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Wouldn't it be better to handle this in pysqlite_do_all_statements, as it has multiple callers? Perhaps pysqlite_do_all_statements could be split in two: do_all_statements and do_all_cursors. Each of them would do a pointer sanity check before looping.

@lielfr lielfr May 2, 2021

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Are you sure about splitting pysqlite_do_all_statements into two functions? It seems like it always performs the statements part, but optionally also performs the cursors part.

@erlend-aasland erlend-aasland May 2, 2021

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No, I'm not sure :) Let's leave it as it is; both pysqlite_do_all_statements and this particular change.

Nit: if (self->statements == NULL) is more explicit, and I believe more consistent with the rest of the code base.


if (!pysqlite_check_thread(self)) {
return NULL;
Expand Down Expand Up @@ -1225,6 +1251,11 @@ int pysqlite_check_thread(pysqlite_Connection* self)

static PyObject* pysqlite_connection_get_isolation_level(pysqlite_Connection* self, void* unused)
{
if (!self || !self->isolation_level) {
PyErr_Format(pysqlite_ProgrammingError,
"Object is null or isolation_level is uninitialized.");
return 0;
}
Comment on lines +1254 to +1258

@erlend-aasland erlend-aasland Apr 30, 2021

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If self->initialized is only set if pysqlite_connection_init was successful, this can be reduced to:

Suggested change
if (!self || !self->isolation_level) {
PyErr_Format(pysqlite_ProgrammingError,
"Object is null or isolation_level is uninitialized.");
return 0;
}
if (!pysqlite_check_connection(self)) {
return NULL;
}

return Py_NewRef(self->isolation_level);
}

Expand Down