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bpo-23691: Protect the re.finditer() iterator from re-entering (GH-32012
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serhiy-storchaka authored Mar 21, 2022
1 parent e63894b commit 08eb754
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Showing 3 changed files with 42 additions and 4 deletions.
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Protect the :func:`re.finditer` iterator from re-entering.
44 changes: 40 additions & 4 deletions Modules/_sre.c
Original file line number Diff line number Diff line change
Expand Up @@ -2511,6 +2511,25 @@ scanner_dealloc(ScannerObject* self)
Py_DECREF(tp);
}

static int
scanner_begin(ScannerObject* self)
{
if (self->executing) {
PyErr_SetString(PyExc_ValueError,
"regular expression scanner already executing");
return 0;
}
self->executing = 1;
return 1;
}

static void
scanner_end(ScannerObject* self)
{
assert(self->executing);
self->executing = 0;
}

/*[clinic input]
_sre.SRE_Scanner.match
Expand All @@ -2528,16 +2547,23 @@ _sre_SRE_Scanner_match_impl(ScannerObject *self, PyTypeObject *cls)
PyObject* match;
Py_ssize_t status;

if (state->start == NULL)
if (!scanner_begin(self)) {
return NULL;
}
if (state->start == NULL) {
scanner_end(self);
Py_RETURN_NONE;
}

state_reset(state);

state->ptr = state->start;

status = sre_match(state, PatternObject_GetCode(self->pattern));
if (PyErr_Occurred())
if (PyErr_Occurred()) {
scanner_end(self);
return NULL;
}

match = pattern_new_match(module_state, (PatternObject*) self->pattern,
state, status);
Expand All @@ -2549,6 +2575,7 @@ _sre_SRE_Scanner_match_impl(ScannerObject *self, PyTypeObject *cls)
state->start = state->ptr;
}

scanner_end(self);
return match;
}

Expand All @@ -2570,16 +2597,23 @@ _sre_SRE_Scanner_search_impl(ScannerObject *self, PyTypeObject *cls)
PyObject* match;
Py_ssize_t status;

if (state->start == NULL)
if (!scanner_begin(self)) {
return NULL;
}
if (state->start == NULL) {
scanner_end(self);
Py_RETURN_NONE;
}

state_reset(state);

state->ptr = state->start;

status = sre_search(state, PatternObject_GetCode(self->pattern));
if (PyErr_Occurred())
if (PyErr_Occurred()) {
scanner_end(self);
return NULL;
}

match = pattern_new_match(module_state, (PatternObject*) self->pattern,
state, status);
Expand All @@ -2591,6 +2625,7 @@ _sre_SRE_Scanner_search_impl(ScannerObject *self, PyTypeObject *cls)
state->start = state->ptr;
}

scanner_end(self);
return match;
}

Expand All @@ -2608,6 +2643,7 @@ pattern_scanner(_sremodulestate *module_state,
if (!scanner)
return NULL;
scanner->pattern = NULL;
scanner->executing = 0;

/* create search state object */
if (!state_init(&scanner->state, self, string, pos, endpos)) {
Expand Down
1 change: 1 addition & 0 deletions Modules/sre.h
Original file line number Diff line number Diff line change
Expand Up @@ -89,6 +89,7 @@ typedef struct {
PyObject_HEAD
PyObject* pattern;
SRE_STATE state;
int executing;
} ScannerObject;

#endif

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