Bug 1541558 (CVE-2018-1000030)

Summary:	CVE-2018-1000030 python: Heap-Buffer-Overflow and Heap-Use-After-Free in Objects/fileobject.c
Product:	[Other] Security Response	Reporter:	Laura Pardo <lpardo>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	extras-orphan, hhorak, jorton, python-maint
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	python 2.7.15	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-02-06 02:05:11 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1541559
Bug Blocks:	1541563

Description Laura Pardo 2018-02-02 21:46:41 UTC

Python 2.7.x is vulnerable to a Heap-Buffer-Overflow as well as a Heap-Use-After-Free. The vulnerability lies when multiply threads are handling large amounts of data. In both cases there is essentially a race condition that occurs. For the Heap-Buffer-Overflow, Thread 2 is creating the size for a buffer, but Thread1 is already writing to the buffer without knowing how much to write. So when a large amount of data is being processed, it is very easy to cause memory corruption using a Heap-Buffer-Overflow. As for the Use-After-Free, Thread3->Malloc->Thread1->Free's->Thread2-Re-uses-Free'd Memory.

References:
https://bugs.python.org/issue31530
https://github.com/CVEProject/cvelist/pull/292/files/5dae4ae63f0c19fb7e30b0f9ee1cf21e232209b1#diff-97ec95c41730bace57df441d3f00c9a3
https://drive.google.com/file/d/1oyR9DAZjZK_SCn3mor6NRAYLJS6ueXaY/view
https://www.dropbox.com/sh/sj3ee7xv55j36k7/AADwP-YfOYikBMuy32e0uvPFa?dl=0

Patch:
https://bugs.python.org/file47157/0001-stop-crashes-when-iterating-over-a-file-on-multiple-.patch

Comment 1 Laura Pardo 2018-02-02 21:47:04 UTC

Created python tracking bugs for this issue:

Affects: fedora-all [bug 1541559]

Comment 3 Doran Moppert 2020-01-21 23:22:29 UTC

Statement:

Versions of Python 2 included in Red Hat Enterprise Linux 6 and 7 are affected by this issue. Reading concurrently from the same file handle in multiple threads is inherently unstable, and should not be relied upon in any real program. This issue is not planned to be fixed in future releases.

This CVE assignment was disputed by upstream. While an attack is theoretically possible, it relies on a programming pattern in the vulnerable Python program that is generally considered bad practice if not an outright bug.