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bpo-31455: avoid calling "PyObject_GetAttrString()" with a live exception set #3545

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merged 5 commits into from
Sep 14, 2017
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bpo-31455: avoid calling "PyObject_GetAttrString()" with a live exception set #3545

merged 5 commits into from
Sep 14, 2017

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scoder
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@scoder scoder commented Sep 13, 2017 •
edited by bedevere-bot
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@scoder scoder mentioned this pull request Sep 13, 2017
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@serhiy-storchaka
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Please open an issue on the bug tracker. This isn't a trivial change.

I think that it would be better to silence only AttributeError.

@scoder scoder changed the title Avoid calling "PyObject_GetAttrString()" with a live exception set. bpo-31455: avoid calling "PyObject_GetAttrString()" with a live exception set Sep 13, 2017
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scoder commented Sep 13, 2017

Found as part of #3279, which started showing side-effects due to this bug.

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scoder commented Sep 13, 2017 •
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PR updated, test and News entry added.

serhiy-storchaka
serhiy-storchaka reviewed Sep 14, 2017
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LGTM. I left just few nitpicks.

Lib/test/test_xml_etree.py Outdated

ET.XMLParser(target=RaisingBuilder(what=AttributeError))
for event in ('start', 'data', 'end', 'comment', 'pi'):
ET.XMLParser(target=RaisingBuilder(event, what=AttributeError))
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Close the parser explicitly. Just for the case.

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Done. (Requires parsing something, though.)

Lib/test/test_xml_etree.py Outdated
@@ -2400,6 +2400,29 @@ def _check_sample1_element(self, e):
self.assertEqual(child.tail, 'tail')
self.assertEqual(child.attrib, {})

def test_exceptions(self):
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Wouldn't XMLParserTest be better place? In any case I think it is better to place this method at the end of the class, after testing normal cases.

And maybe use more specific method name? "test_builder_attribute_errors" or something like.

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Done. I kept it in the test class because the exceptions are related to the behaviour of the TreeBuilder.

Modules/_elementtree.c Outdated
@@ -3259,6 +3259,17 @@ xmlparser_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
return (PyObject *)self;
}

static int
ignore_attribute_error(PyObject *value) {
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Put this { on new line.

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Done.

Modules/_elementtree.c Outdated
@@ -3313,14 +3324,26 @@ _elementtree_XMLParser___init___impl(XMLParserObject *self, PyObject *html,
self->target = target;

self->handle_start = PyObject_GetAttrString(target, "start");
if (ignore_attribute_error(self->handle_start))
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New PEP 7 rules require braces even around simple if body.

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Done. (Sad in this case, given the relation between "active" code and error handling code.)

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scoder commented Sep 14, 2017

PR updated.

@serhiy-storchaka serhiy-storchaka added needs backport to 2.7 type-bug An unexpected behavior, bug, or error labels Sep 14, 2017
@serhiy-storchaka serhiy-storchaka merged commit c8d8e15 into python:master Sep 14, 2017
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Thanks @scoder for the PR, and @serhiy-storchaka for merging it 🌮🎉.. I'm working now to backport this PR to: 2.7, 3.6.
🐍🍒⛏🤖

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Sorry, @scoder and @serhiy-storchaka, I could not cleanly backport this to 2.7 due to a conflict.
Please backport using cherry_picker on command line.

miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Sep 14, 2017
@scoder @miss-islington
[3.6] bpo-31455: Fix an assertion failure in ElementTree.XMLParser(). (…
6c3eec6 
…pythonGH-3545)

* Avoid calling "PyObject_GetAttrString()" (and potentially executing user code) with a live exception set.

* Ignore only AttributeError on attribute lookups in ElementTree.XMLParser() and propagate all other exceptions.
(cherry picked from commit c8d8e15)
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GH-3585 is a backport of this pull request to the 3.6 branch.

serhiy-storchaka pushed a commit that referenced this pull request Sep 14, 2017
@miss-islington @serhiy-storchaka
[3.6] bpo-31455: Fix an assertion failure in ElementTree.XMLParser(). (…
49caab4 
…GH-3545) (#3585)

* Avoid calling "PyObject_GetAttrString()" (and potentially executing user code) with a live exception set.

* Ignore only AttributeError on attribute lookups in ElementTree.XMLParser() and propagate all other exceptions.
(cherry picked from commit c8d8e15)
@miss-islington
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Thanks @scoder for the PR, and @serhiy-storchaka for merging it 🌮🎉.. I'm working now to backport this PR to: 2.7.
🐍🍒⛏🤖

@miss-islington
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Sorry, @scoder and @serhiy-storchaka, I could not cleanly backport this to 2.7 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker c8d8e15bfc24abeeaaf3d8be9073276b0c011cdf 2.7

@scoder scoder mentioned this pull request Oct 14, 2017
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