Bug 1512414 – tevent can cause a Samba file corruption bug under heavy threaded load

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Bug 1512414 - tevent can cause a Samba file corruption bug under heavy threaded load

Summary:	tevent can cause a Samba file corruption bug under heavy threaded load

Status:	CLOSED ERRATA

Aliases:	None

Product:	Red Hat Enterprise Linux 7
Classification:	Red Hat
Component:	libtevent (Show other bugs)
Sub Component:
Version:	7.4
Hardware:	Unspecified Unspecified

Priority	urgent Severity urgent
Target Milestone:	rc
Target Release:	---
Assigned To:	Jakub Hrozek
QA Contact:	shridhar
Docs Contact:

URL:
Whiteboard:
Keywords:	ZStream

Depends On:
Blocks:	1513984
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Reported:	2017-11-13 02:30 EST by Andreas Schneider
Modified:	2018-04-23 03:58 EDT (History)
CC List:	5 users (show)

See Also:
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 12:14:52 EDT
Type:	Bug
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

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External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Samba Project	13130	None	None	None	2017-11-13 02:30 EST
Red Hat Product Errata	RHBA-2018:0887	None	None	None	2018-04-10 12:15 EDT

Groups: None (edit)

Description Andreas Schneider 2017-11-13 02:30:14 EST

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 02:32:52 EST

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 06:36:01 EST

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

Comment 8 shridhar 2017-12-01 02:52:08 EST

How to verify this bug?

Comment 9 Jakub Hrozek 2017-12-03 15:22:41 EST

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

Just with regression testing.

Comment 10 shridhar 2017-12-21 06:50:44 EST

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

Comment 11 Andreas Schneider 2018-01-02 08:53:37 EST

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

Comment 14 errata-xmlrpc 2018-04-10 12:14:52 EDT

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

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