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Merged
sobolevn merged 5 commits into from
Apr 7, 2025
Merged

gh-130775: Allow negative locations in ast #130795

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fd105a8
gh-130775: Validate negative locations in `ast`
sobolevn Mar 3, 2025
9d2037e
Update Python/ast.c
sobolevn Mar 3, 2025
1427c57
Address reviews
sobolevn Mar 13, 2025
97f4efb
Merge branch 'main' into issue-130775
sobolevn Mar 13, 2025
8f3e1a9
Fix tests
sobolevn Mar 13, 2025
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21 changes: 21 additions & 0 deletions Lib/test/test_ast/test_ast.py
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Expand Up @@ -204,6 +204,27 @@ def test_compilation_of_ast_nodes_with_default_end_position_values(self):
# Check that compilation doesn't crash. Note: this may crash explicitly only on debug mode.
compile(tree, "<string>", "exec")

def test_compilation_of_ast_nodes_with_negative_position_values(self):
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# See https://github.com/python/cpython/issues/130775
alias = ast.alias(name='traceback', lineno=0, col_offset=0)
for attrs in (
{'lineno': -2, 'col_offset': 0},
{'lineno': 0, 'col_offset': -2},
{'lineno': 0, 'col_offset': -2, 'end_col_offset': -2},
{'lineno': -2, 'end_lineno': -2, 'col_offset': 0},
Comment on lines +211 to +214

@picnixz picnixz Mar 3, 2025

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  • Off topic: are we already testing that passing a non-int is fine?
  • Maybe test with values that are excessively large (either in + or -) just for overflow checks.

@sobolevn sobolevn Mar 3, 2025

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I will open a new issue for that, if we don't. Thanks for the idea.

):
with self.subTest(attrs=attrs):
tree = ast.Module(body=[
ast.Import(names=[alias], **attrs)
], type_ignores=[])

# It used to crash on this step:
with self.assertRaisesRegex(
ValueError,
'AST node has invalid location',
):
compile(tree, "<string>", "exec")
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def test_slice(self):
slc = ast.parse("x[::]").body[0].value.slice
self.assertIsNone(slc.upper)
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core_and_Builtins/2025-03-03-20-02-45.gh-issue-130775.fEM6T-.rst
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@@ -0,0 +1,2 @@
Validate negative :mod:`ast` locations, we only allow ``-1`` as a special
value.
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1 change: 1 addition & 0 deletions Python/assemble.c
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Expand Up @@ -297,6 +297,7 @@ write_location_info_entry(struct assembler* a, location loc, int isize)
int line_delta = loc.lineno - a->a_lineno;
int column = loc.col_offset;
int end_column = loc.end_col_offset;
// Values are validated in `VALIDATE_POSITIONS` in `ast.c`:
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assert(column >= -1);
assert(end_column >= -1);
if (column < 0 || end_column < 0) {
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9 changes: 9 additions & 0 deletions Python/ast.c
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Expand Up @@ -40,6 +40,15 @@ static int validate_typeparam(type_param_ty);
node->col_offset, node->end_col_offset, node->lineno, node->end_lineno); \
return 0; \
} \
if (node->lineno < -1 || node->end_lineno < -1 || \
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node->col_offset < -1 || node->end_col_offset < -1) { \
PyErr_Format(PyExc_ValueError, \
"AST node has invalid location: lineno=%d, end_lineno=%d, " \
"col_offset=%d, end_col_offset=%d", \
node->lineno, node->end_lineno, \
node->col_offset, node->end_col_offset); \
return 0; \
} \
if (node->lineno == node->end_lineno && node->col_offset > node->end_col_offset) { \
PyErr_Format(PyExc_ValueError, \
"line %d, column %d-%d is not a valid range", \
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