Message 285921 - Python tracker

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Author	Zach Riggle
Recipients	Zach Riggle
Date	2017-01-20.20:48:07
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<[email protected]>
In-reply-to

Content
The attached script hits some "This should never happen" code in the subprocess module. These lines here: https://github.com/python/cpython/blob/2.7/Lib/subprocess.py#L1036-L1038 The root cause is a lack of checking WIFSTOPPED and WSTOPSIG in the handler. When a process elects into being ptraced via PTRACE_TRACEME, it is stopped on the SIGSEGV instead of terminating, allowing the user to attach a debugger before the kernel destroys the process. This bug makes it impossible to wait on any process which crashes, which is set up to wait for a debugger.

The attached script hits some "This should never happen" code in the subprocess module.

These lines here:
https://github.com/python/cpython/blob/2.7/Lib/subprocess.py#L1036-L1038

The root cause is a lack of checking WIFSTOPPED and WSTOPSIG in the handler.

When a process elects into being ptraced via PTRACE_TRACEME, it is stopped on the SIGSEGV instead of terminating, allowing the user to attach a debugger before the kernel destroys the process.

This bug makes it impossible to wait on any process which crashes, which is set up to wait for a debugger.

History
Date	User	Action	Args
2017-01-20 20:48:08	Zach Riggle	set	recipients: + Zach Riggle
2017-01-20 20:48:08	Zach Riggle	set	messageid: <[email protected]>
2017-01-20 20:48:08	Zach Riggle	link	issue29335 messages
2017-01-20 20:48:08	Zach Riggle	create