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Validate config key names before writing #2142

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e226e42
Validate config key names before writing
codex May 5, 2026
9c92f22
Fix mypy section-name validation type
codex May 5, 2026
74a0d56
Address review feedback for config validation
codex May 5, 2026
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17 changes: 16 additions & 1 deletion git/config.py
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Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,9 @@
See: https://git-scm.com/docs/git-config#_conditional_includes
"""

UNSAFE_CONFIG_CHARS_RE = re.compile(r"[\r\n\x00]")
"""Characters that cannot be safely written in config names or values."""


class MetaParserBuilder(abc.ABCMeta): # noqa: B024
"""Utility class wrapping base-class methods into decorators that assure read-only
Expand Down Expand Up @@ -778,6 +781,7 @@ def _assure_writable(self, method_name: str) -> None:

def add_section(self, section: "cp._SectionName") -> None:
"""Assures added options will stay in order."""
self._assure_config_name_safe(section, "section")
return super().add_section(section)

@property
Expand Down Expand Up @@ -884,10 +888,14 @@ def _value_to_string(self, value: Union[str, bytes, int, float, bool]) -> str:

def _value_to_string_safe(self, value: Union[str, bytes, int, float, bool]) -> str:
value_str = self._value_to_string(value)
if re.search(r"[\r\n\x00]", value_str):
if UNSAFE_CONFIG_CHARS_RE.search(value_str):
raise ValueError("Git config values must not contain CR, LF, or NUL")
return value_str

def _assure_config_name_safe(self, name: "cp._SectionName", label: str) -> None:
if isinstance(name, str) and UNSAFE_CONFIG_CHARS_RE.search(name):
raise ValueError("Git config %s names must not contain CR, LF, or NUL" % label)

@needs_values
@set_dirty_and_flush_changes
def set(
Expand All @@ -896,6 +904,8 @@ def set(
option: str,
value: Union[str, bytes, int, float, bool, None] = None,
) -> None:
self._assure_config_name_safe(section, "section")
self._assure_config_name_safe(option, "option")
if value is not None:
value = self._value_to_string_safe(value)
return super().set(section, option, value)
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Expand All @@ -920,6 +930,8 @@ def set_value(self, section: str, option: str, value: Union[str, bytes, int, flo
:return:
This instance
"""
self._assure_config_name_safe(section, "section")
self._assure_config_name_safe(option, "option")
value_str = self._value_to_string_safe(value)
if not self.has_section(section):
self.add_section(section)
Expand Down Expand Up @@ -948,6 +960,8 @@ def add_value(self, section: str, option: str, value: Union[str, bytes, int, flo
:return:
This instance
"""
self._assure_config_name_safe(section, "section")
self._assure_config_name_safe(option, "option")
value_str = self._value_to_string_safe(value)
if not self.has_section(section):
self.add_section(section)
Expand All @@ -968,6 +982,7 @@ def rename_section(self, section: str, new_name: str) -> "GitConfigParser":
"""
if not self.has_section(section):
raise ValueError("Source section '%s' doesn't exist" % section)
self._assure_config_name_safe(new_name, "section")
if self.has_section(new_name):
raise ValueError("Destination section '%s' already exists" % new_name)

Expand Down
31 changes: 31 additions & 0 deletions test/test_config.py
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Original file line number Diff line number Diff line change
Expand Up @@ -163,6 +163,37 @@ def test_set_value_rejects_config_injection(self, rw_dir):
self.assertFalse(git_config.has_section("user"))
self.assertFalse(git_config.has_section("core"))

@with_rw_directory
def test_set_value_rejects_unsafe_section_and_option_names(self, rw_dir):
config_path = osp.join(rw_dir, "config")
bad_keys = ("user]\n[core", "user]\r[core", "user]\x00[core")

with GitConfigParser(config_path, read_only=False) as git_config:
git_config.add_section("user")
for bad_key in bad_keys:
with pytest.raises(ValueError, match="CR, LF, or NUL"):
git_config.add_section(bad_key)
with pytest.raises(ValueError, match="CR, LF, or NUL"):
git_config.set(bad_key, "hooksPath", "/tmp/hooks")
with pytest.raises(ValueError, match="CR, LF, or NUL"):
git_config.set("user", bad_key, "/tmp/hooks")
with pytest.raises(ValueError, match="CR, LF, or NUL"):
git_config.set_value(bad_key, "hooksPath", "/tmp/hooks")
with pytest.raises(ValueError, match="CR, LF, or NUL"):
git_config.set_value("user", bad_key, "/tmp/hooks")
with pytest.raises(ValueError, match="CR, LF, or NUL"):
git_config.add_value(bad_key, "hooksPath", "/tmp/hooks")
with pytest.raises(ValueError, match="CR, LF, or NUL"):
git_config.add_value("user", bad_key, "/tmp/hooks")
with pytest.raises(ValueError, match="CR, LF, or NUL"):
git_config.rename_section("user", bad_key)

git_config.set_value("user", "name", "safe")

with GitConfigParser(config_path, read_only=True) as git_config:
self.assertEqual(git_config.get_value("user", "name"), "safe")
self.assertFalse(git_config.has_section("core"))

@with_rw_directory
def test_set_and_add_value_reject_unsafe_value_characters(self, rw_dir):
config_path = osp.join(rw_dir, "config")
Expand Down
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