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GeezerVison is showing github.com — bpo-40661: Fix segfaults when parsing invalid input by gvanrossum · Pull Request #20159 · python/cpython

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@gvanrossum

@gvanrossum gvanrossum commented May 17, 2020 •
edited by bedevere-bot
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Fixes bpo-40661. (In fact this just is the patch from @pablogsal from
that issue.)

Note that for an extreme benchmark (xxl.py) this caused a 40% slowdown
on my Mac. However for an "average" benchmark (stdlib) there was no
significant difference.

https://bugs.python.org/issue40661

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@gvanrossum
Fix segfaults when parsing invalid input
9b632e9 
Fixes bpo-40661.  (In fact this just is the patch from @pablogsal from
that issue.)

Note that for an extreme benchmark (xxl.py) this caused a 40% slowdown
on my Mac.  However for an "average" benchmark (stdlib) there was no
significant difference.
@gvanrossum
gvanrossum requested review from lysnikolaou and pablogsal May 17, 2020 18:14
@the-knights-who-say-ni the-knights-who-say-ni added the CLA signed label May 17, 2020
@bedevere-bot bedevere-bot added the awaiting core review label May 17, 2020
@gvanrossum gvanrossum added the skip news label May 17, 2020
@gvanrossum gvanrossum changed the title Fix segfaults when parsing invalid input bpo-40661: Fix segfaults when parsing invalid input May 17, 2020
@lysnikolaou

lysnikolaou commented May 17, 2020

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reproducer.py, the file @pablogsal uploaded on the issue, does not segfault even if we only check for p->error_indicator == 1 and leave the call to PyErr_Occurred() out.
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lysnikolaou
lysnikolaou reviewed May 17, 2020
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Comment thread Tools/peg_generator/pegen/c_generator.py
Comment on lines +684 to +688
self.print("if (p->error_indicator == 1 || PyErr_Occurred()) {")
with self.indent():
self.print("p->error_indicator = 1;")
self.print("return NULL;")
self.print("}")

@lysnikolaou lysnikolaou May 17, 2020

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I'd actually move this within the scope block of the alternative (after the with self.indent() below).

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@gvanrossum

gvanrossum commented May 17, 2020 via email

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Lysandros, can you take over responsibility for this PR? I'm just out of energy for this.
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@lysnikolaou

lysnikolaou commented May 17, 2020

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Yes, of course! Should we close it and open a new one, since I can't push to a branch of the upstream repo?
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@gvanrossum

gvanrossum commented May 17, 2020 via email

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Sure.
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@lysnikolaou

lysnikolaou commented May 17, 2020

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Ok, closing.
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@lysnikolaou lysnikolaou closed this May 17, 2020
@zware
zware deleted the fix-segfaults branch May 18, 2020 23:05
@gvanrossum

gvanrossum commented May 19, 2020

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Note that for an extreme benchmark (xxl.py) this caused a 40% slowdown
on my Mac. However for an "average" benchmark (stdlib) there was no
significant difference.

To follow up: I believe this may have been an exaggerated outcome because I built with debug flags on (and had forgotten about it).
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@lysnikolaou lysnikolaou lysnikolaou left review comments
@pablogsal pablogsal Awaiting requested review from pablogsal

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@gvanrossum @lysnikolaou @the-knights-who-say-ni @bedevere-bot
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