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PyDict_SetItemString() fails when the second argument is null #49877

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eulerto mannequin opened this issue Mar 31, 2009 · 7 comments
Closed

PyDict_SetItemString() fails when the second argument is null #49877

eulerto mannequin opened this issue Mar 31, 2009 · 7 comments
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@birkenfeld
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interpreter-core (Objects, Python, Grammar, and Parser dirs) type-crash A hard crash of the interpreter, possibly with a core dump

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@eulerto
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eulerto mannequin commented Mar 31, 2009

BPO 5627
Nosy @loewis, @birkenfeld, @rhettinger

Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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GitHub fields:

assignee = 'https://github.com/birkenfeld'
closed_at = <Date 2009-04-02.02:52:51.436>
created_at = <Date 2009-03-31.16:47:12.008>
labels = ['interpreter-core', 'type-crash']
title = 'PyDict_SetItemString() fails when the second argument is\tnull'
updated_at = <Date 2009-04-02.02:52:51.415>
user = 'https://bugs.python.org/eulerto'

bugs.python.org fields:

activity = <Date 2009-04-02.02:52:51.415>
actor = 'georg.brandl'
assignee = 'georg.brandl'
closed = True
closed_date = <Date 2009-04-02.02:52:51.436>
closer = 'georg.brandl'
components = ['Interpreter Core']
creation = <Date 2009-03-31.16:47:12.008>
creator = 'eulerto'
dependencies = []
files = []
hgrepos = []
issue_num = 5627
keywords = []
message_count = 7.0
messages = ['84833', '84851', '84978', '84983', '85114', '85142', '85145']
nosy_count = 4.0
nosy_names = ['loewis', 'georg.brandl', 'rhettinger', 'eulerto']
pr_nums = []
priority = 'normal'
resolution = 'wont fix'
stage = None
status = 'closed'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue5627'
versions = []
@eulerto
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Mannequin Author

eulerto mannequin commented Mar 31, 2009

PyDict_SetItemString() fails when the second argument (key) is null
pointer. It occurs because PyString_FromString(key) call doesn't check
for null pointer and if we're in a disabled assert environment the
assert() is not caught and strlen() fails.

I don't know what is the best fix but we have two possibilities:

(i) check the second argument in PyDict_SetItemString() before calling
PyString_FromString() and returns null if that argument is null;
(ii) replace the assert() in PyString_FromString() to 'if (str == NULL)
return NULL;'.

This bug was reported as a PostgreSQL bug at [1].

[1] http://archives.postgresql.org/pgsql-hackers/2009-03/msg01344.php

@eulerto eulerto mannequin added interpreter-core (Objects, Python, Grammar, and Parser dirs) type-crash A hard crash of the interpreter, possibly with a core dump labels Mar 31, 2009
@eulerto
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eulerto mannequin commented Mar 31, 2009

It seems PyDict_DelItemString() and PyDict_SetItem() suffer from the
same disease. :( Both use assert() to detect a null pointer but fail to
prevent it. As I stated in the previous comment, maybe the right fix is
to replace assert() with the 'if (foo == NULL) return whatever'.

@birkenfeld
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I am not sure why you consider this a bug. You should certainly not pass
NULL pointers around where the docs do not explicitly allow this.

@eulerto
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eulerto mannequin commented Apr 1, 2009

I know that it is a good programming practice checking null pointers but
sometimes programmers are lazy. ;) I still think that high level
functions should check for null pointers.

@birkenfeld
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Raymond, do you have an opinion about this?

@rhettinger rhettinger assigned loewis and unassigned rhettinger Apr 2, 2009
@loewis loewis mannequin changed the title PyDict_SetItemString() fails when the second argument is null PyDict_SetItemString() fails when the second argument is null Apr 2, 2009
@rhettinger
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I recommend rejecting this one. The assert is sufficient for
third-party modules to run their tests and detect bad calls. The code
path is too critical to add another check.

@rhettinger rhettinger assigned birkenfeld and unassigned loewis Apr 2, 2009
@birkenfeld
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Closing.

@ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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