Bug 1682954

Summary:	glibc: Call _dl_open_check (CET related) after relocation is finished
Product:	Red Hat Enterprise Linux 8	Reporter:	Carlos O'Donell <codonell>
Component:	glibc	Assignee:	DJ Delorie <dj>
Status:	CLOSED ERRATA	QA Contact:	qe-baseos-tools-bugs
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	8.0	CC:	ashankar, codonell, dj, fweimer, mcermak, mnewsome, pfrankli, skolosov, tgummels, woodard
Target Milestone:	rc	Keywords:	Patch, Triaged
Target Release:	8.0
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	glibc-2.28-82.el8	Doc Type:	No Doc Update
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-04-28 16:50:14 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Bug Depends On:	1682593
Bug Blocks:	1755139, 1746913

Description Carlos O'Donell 2019-02-25 22:35:15 UTC

When dlopening a shared object, _dl_open_check will throw an exception
if CET shadow stack is enabled and the shared object has no shadow stack
support.  dl_open_worker must call _dl_open_check after relocation is
finished.  Otherwise, the dependency shared objects may be mmapped
without relocation.  This will lead to run-time failure later when they
are needed by another dlopened shared object which is shadow stack
enabled.

https://sourceware.org/ml/libc-alpha/2019-02/msg00579.html

https://sourceware.org/bugzilla/show_bug.cgi?id=24259

Comment 8 Florian Weimer 2019-08-30 11:18:12 UTC

Note: My understanding is that this bug is visible even on non-CET hardware because the CET markup is checked for consistency even in non-CET mode, which makes this bug visible on current x86 hardware.

Comment 10 Carlos O'Donell 2019-10-22 13:54:21 UTC

Commit:

commit d0093c5cefb7f7a4143f3bb03743633823229cc6
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Mon Jul 1 12:23:10 2019 -0700

    Call _dl_open_check after relocation [BZ #24259]
    
    This is a workaround for [BZ #20839] which doesn't remove the NODELETE
    object when _dl_open_check throws an exception.  Move it after relocation
    in dl_open_worker to avoid leaving the NODELETE object mapped without
    relocation.

Please also verify upstream branch backports:

release/2.30/master - May be required. Please check.
release/2.29/master - May be required. Please check.
release/2.28/master - May be required. Please check.

Comment 11 DJ Delorie 2019-11-01 19:30:28 UTC

Backported to upstream 2.29 and 2.28

Comment 14 Sergey Kolosov 2020-03-17 18:31:07 UTC

Verified with elf/tst-cet-legacy-5a, elf/tst-cet-legacy-6a

Comment 16 errata-xmlrpc 2020-04-28 16:50:14 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2020:1828