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bpo-42609: Check recursion depth in the AST validator and optimizer #23744

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Merged
merged 5 commits into from
Apr 25, 2021
Merged

bpo-42609: Check recursion depth in the AST validator and optimizer #23744

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8c5cb1e
bpo-42609: Check recursion depth in the AST validator and optimizer
serhiy-storchaka Dec 10, 2020
8d3a7a2
Check recursion depth in validate_constant().
serhiy-storchaka Dec 16, 2020
364d0d2
Fix typo
serhiy-storchaka Dec 16, 2020
e0e64e2
Merge branch 'master' into ast-validator-optimizer-recursion-error
serhiy-storchaka Apr 25, 2021
8c53a01
Add an explainating comment for crashing tests
serhiy-storchaka Apr 25, 2021
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3 changes: 3 additions & 0 deletions Include/internal/pycore_compile.h
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,9 @@ extern PyObject* _Py_Mangle(PyObject *p, PyObject *name);
typedef struct {
int optimize;
int ff_features;

int recursion_depth; /* current recursion depth */
int recursion_limit; /* recursion limit */
} _PyASTOptimizeState;

extern int _PyAST_Optimize(
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19 changes: 12 additions & 7 deletions Lib/test/test_compile.py
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Expand Up @@ -543,21 +543,26 @@ def test_compiler_recursion_limit(self):
# XXX (ncoghlan): duplicating the scaling factor here is a little
# ugly. Perhaps it should be exposed somewhere...
fail_depth = sys.getrecursionlimit() * 3
crash_depth = sys.getrecursionlimit() * 300
success_depth = int(fail_depth * 0.75)

def check_limit(prefix, repeated):
def check_limit(prefix, repeated, mode="single"):
expect_ok = prefix + repeated * success_depth
self.compile_single(expect_ok)
broken = prefix + repeated * fail_depth
details = "Compiling ({!r} + {!r} * {})".format(
prefix, repeated, fail_depth)
with self.assertRaises(RecursionError, msg=details):
self.compile_single(broken)
compile(expect_ok, '<test>', mode)
for depth in (fail_depth, crash_depth):
broken = prefix + repeated * depth
details = "Compiling ({!r} + {!r} * {})".format(
prefix, repeated, depth)
Comment on lines +554 to +555
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An f-string could be used.

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Yes, but this code already was here.

with self.assertRaises(RecursionError, msg=details):
compile(broken, '<test>', mode)

check_limit("a", "()")
check_limit("a", ".b")
check_limit("a", "[0]")
check_limit("a", "*a")
# XXX Crashes in the parser.
# check_limit("a", " if a else a")
# check_limit("if a: pass", "\nelif a: pass", mode="exec")

def test_null_terminated(self):
# The source code is null-terminated internally, but bytes-like
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2020-12-12-14-28-31.bpo-42609.Qcd54b.rst
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@@ -0,0 +1,3 @@
Prevented crashes in the AST validator and optimizer when compiling some
absurdly long expressions like ``"+0"*1000000``. :exc:`RecursionError` is
now raised instead.
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