Bug 1534076

Summary:	util-linux: mount/unmount ASLR bypass via environment variable in libmount
Product:	[Other] Security Response	Reporter:	Laura Pardo <lpardo>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	jonathan, kzak, slawomir
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:
Clones:	1534893 (view as bug list)		Environment:
Last Closed:	2019-06-08 03:37:03 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:	1534077, 1536164
Bug Blocks:	1534893, 1535102

Description Laura Pardo 2018-01-13 00:13:35 UTC

Debugging of libmount can be activated, also in SUID binaries, thus spilling out the heap addresses. This allows to create a local domain socket with only 4k buffer size, fill it up until writes are blocking and then start umount with that socket as stdout. This allows race-free reading of the address output before umount accesses other user-controlled resource. Thus any error during the downstream procedure creating some kind of write-where vulnerability will always find the correct target.

References:
https://www.spinics.net/lists/util-linux-ng/msg14978.html

Comment 1 Laura Pardo 2018-01-13 00:14:03 UTC

Created util-linux tracking bugs for this issue:

Affects: fedora-all [bug 1534077]

Comment 2 Cedric Buissart 2018-01-17 10:08:32 UTC

Upstream fix : 
https://git.kernel.org/pub/scm/utils/util-linux/util-linux.git/commit/?h=6d00cfb2330cb47d00d350eedfbffbbf5991a743

Comment 4 Pedro Yóssis Silva Barbosa 2018-01-18 18:32:06 UTC

Statement:

This issue did not affect the versions of util-linux as shipped with Red Hat Enterprise Linux 4, 5, 6 and 7.