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bpo-11105: Do not crash when compiling recursive ASTs (GH-20594)

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When compiling an AST object with a direct / indirect reference
cycles, on the conversion phase because of exceeding amount of
calls, a segfault was raised. This patch adds recursion guards to
places for preventing user inputs to not to crash AST but instead
raise a RecursionError.
This commit is contained in:
Batuhan Taskaya 2021-06-03 23:01:02 +03:00 • committed by GitHub
parent f461a7fc3f
commit f3491242e4
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4 changed files with 840 additions and 4 deletions
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19
Parser/asdl_c.py
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@ -6,6 +6,7 @@ import sys
import textwrap
from argparse import ArgumentParser
from contextlib import contextmanager
from pathlib import Path
import asdl
@ -421,6 +422,14 @@ class Obj2ModPrototypeVisitor(PickleVisitor):
class Obj2ModVisitor(PickleVisitor):
@contextmanager
def recursive_call(self, node, level):
self.emit('if (Py_EnterRecursiveCall(" while traversing \'%s\' node")) {' % node, level, reflow=False)
self.emit('goto failed;', level + 1)
self.emit('}', level)
yield
self.emit('Py_LeaveRecursiveCall();', level)
def funcHeader(self, name):
ctype = get_c_type(name)
self.emit("int", 0)
@ -596,8 +605,9 @@ class Obj2ModVisitor(PickleVisitor):
self.emit("%s val;" % ctype, depth+2)
self.emit("PyObject *tmp2 = PyList_GET_ITEM(tmp, i);", depth+2)
self.emit("Py_INCREF(tmp2);", depth+2)
self.emit("res = obj2ast_%s(state, tmp2, &val, arena);" %
field.type, depth+2, reflow=False)
with self.recursive_call(name, depth+2):
self.emit("res = obj2ast_%s(state, tmp2, &val, arena);" %
field.type, depth+2, reflow=False)
self.emit("Py_DECREF(tmp2);", depth+2)
self.emit("if (res != 0) goto failed;", depth+2)
self.emit("if (len != PyList_GET_SIZE(tmp)) {", depth+2)
@ -610,8 +620,9 @@ class Obj2ModVisitor(PickleVisitor):
self.emit("asdl_seq_SET(%s, i, val);" % field.name, depth+2)
self.emit("}", depth+1)
else:
self.emit("res = obj2ast_%s(state, tmp, &%s, arena);" %
(field.type, field.name), depth+1)
with self.recursive_call(name, depth+1):
self.emit("res = obj2ast_%s(state, tmp, &%s, arena);" %
(field.type, field.name), depth+1)
self.emit("if (res != 0) goto failed;", depth+1)
self.emit("Py_CLEAR(tmp);", depth+1)