Bug 1512414

Summary:	tevent can cause a Samba file corruption bug under heavy threaded load
Product:	Red Hat Enterprise Linux 7	Reporter:	Andreas Schneider <asn>
Component:	libtevent	Assignee:	Jakub Hrozek <jhrozek>
Status:	CLOSED ERRATA	QA Contact:	shridhar <sgadekar>
Severity:	urgent	Docs Contact:
Priority:	urgent
Version:	7.4	CC:	asn, enewland, jhrozek, sgoveas, tscherf
Target Milestone:	rc	Keywords:	ZStream
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	libtevent-0.9.33-2.el7	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:
Clones:	1513984 (view as bug list)		Environment:
Last Closed:	2018-04-10 16:14:52 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:
Embargoed:
Bug Depends On:
Bug Blocks:	1513984

Description Andreas Schneider 2017-11-13 07:30:14 UTC

Description of problem:
A race condition in the tevent threaded code can cause tevent_common_wakeup_fd(tctx->wakeup_fd) to be called where wakeup_fd is being read out of reused memory unprotected by mutex lock (tctx may no longer exist).

If the reused memory happens to point to a wakeup_fd value that matches a file descriptor in use by smbd to write to a on-disk file, file corruption will result.

Comment 1 Andreas Schneider 2017-11-13 07:32:52 UTC

This bug is for Samba more important than a security release because it can corrupt on disk data we try to avoid in any circumstance!

Comment 5 Andreas Schneider 2017-11-14 11:36:01 UTC

I don't think so or there would be one in the upstream testsuite.

Comment 8 shridhar 2017-12-01 07:52:08 UTC

How to verify this bug?

Comment 9 Jakub Hrozek 2017-12-03 20:22:41 UTC

(In reply to shridhar from comment #8)
> How to verify this bug?

Just with regression testing.

Comment 10 shridhar 2017-12-21 11:50:44 UTC

verified with  sssd-1.16.0-9.el7.x86_64 
No error/failures found from regression runs

Comment 11 Andreas Schneider 2018-01-02 13:53:37 UTC

Run the tevent test suite. I think it is part of the RPM build ...

Comment 14 errata-xmlrpc 2018-04-10 16:14:52 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/RHBA-2018:0887