Bug 1641878 (CVE-2018-18559)

Summary: CVE-2018-18559 kernel: Use-after-free due to race condition in AF_PACKET implementation
Product: [Other] Security Response Reporter: Sam Fowler <sfowler>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: abhgupta, acaringi, airlied, asavkov, bhu, blc, brdeoliv, bskeggs, dbaker, dhoward, dvlasenk, eshatokhin, ewk, fhrbata, hdegoede, hkrzesin, hwkernel-mgr, iboverma, ichavero, itamar, jarodwilson, jforbes, jglisse, jkacur, joe.lawrence, john.j5live, jokerman, jonathan, josef, jpoimboe, jross, jstancek, jwboyer, kernel-maint, kernel-mgr, labbott, lgoncalv, linville, matt, mchehab, mcressma, mjg59, mlangsdo, mmilgram, nmurray, plougher, pmatouse, rt-maint, rvrbovsk, slawomir, steved, sthangav, trankin, vdronov, williams, yozone
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
A use-after-free flaw can occur in the Linux kernel due to a race condition between packet_do_bind() and packet_notifier() functions called for an AF_PACKET socket. An unprivileged, local user could use this flaw to induce kernel memory corruption on the system, leading to an unresponsive system or to a crash. Due to the nature of the flaw, privilege escalation cannot be fully ruled out.
Story Points: ---
Clone Of: Environment:
Last Closed: 2019-06-10 10:40:50 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---
Bug Depends On: 1643685, 1695835, 1725173, 1725174, 1641879, 1641880, 1641881, 1643680, 1643681, 1643682, 1643683, 1643684, 1657888, 1717808    
Bug Blocks: 1641883    

Description Sam Fowler 2018-10-23 05:44:59 UTC
A use-after-free flaw can occur in the Linux kernel due to a race condition between packet_do_bind() and packet_notifier() functions called for an AF_PACKET socket. An unprivileged local user could use this flaw to induce kernel memory corruption on the system, leading to an unresponsive system or to a crash. Due to the nature of the flaw, privilege escalation cannot be fully ruled out.

External Reference:

https://blogs.securiteam.com/index.php/archives/3731

A probable fix:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=15fe076edea787807a7cdc168df832544b58eba6

Comment 1 Sam Fowler 2018-10-23 05:46:07 UTC
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1641879]

Comment 3 Evgenii Shatokhin 2018-10-26 10:00:56 UTC
I guess, there is a bit of confusion here.

If I understand it correctly, mainline commit 15fe076edea787807a7cdc168df832544b58eba6 "net/packet: fix a race in packet_bind() and packet_notifier()" is the actual fix for the problem.

It seems, its authors just did not know that the race can lead to an exploitable use-after-free as well.

The kernel 3.10.0-862.14.4 from RHEL7 does not have that mainline fix. Not sure about the newer ones.

By the way, I have checked the exploit on our custom kernel based on 3.10.0-862.11.6 from RHEL 7 - if run as a non-root user, it causes kernel crashes or (in some cases) soft lockups within minutes. I added that patch from mainline, tried the exploit again - no such problems happened this time.

Comment 5 Vladis Dronov 2018-10-26 17:42:32 UTC
(In reply to Evgenii Shatokhin from comment #3)
> If I understand it correctly, mainline commit
> 15fe076edea787807a7cdc168df832544b58eba6 "net/packet: fix a race in
> packet_bind() and packet_notifier()" is the actual fix for the problem.

Evgenii, thank you for your update. Indeed, the wording in the securiteam's article regarding 15fe076edea7 is, at least, unclear.

> I added that patch
> from mainline, tried the exploit again - no such problems happened this time.

Yes, RHEL-7 is vulnerable to this flaw without the commit 15fe076edea7 and looks like behaving correctly with this commit. so, probably this is the fix indeed.

Thank you for your research and confirmation!

Comment 8 Justin M. Forbes 2018-11-01 11:42:12 UTC
This was fixed for Fedora with the 4.15 kernel rebases.

Comment 9 errata-xmlrpc 2019-01-29 17:23:46 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2019:0163 https://access.redhat.com/errata/RHSA-2019:0163

Comment 10 errata-xmlrpc 2019-01-29 17:24:19 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2019:0188 https://access.redhat.com/errata/RHSA-2019:0188

Comment 12 errata-xmlrpc 2019-05-14 19:08:32 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7.4 Extended Update Support

Via RHSA-2019:1170 https://access.redhat.com/errata/RHSA-2019:1170

Comment 13 errata-xmlrpc 2019-05-14 20:26:55 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise MRG 2

Via RHSA-2019:1190 https://access.redhat.com/errata/RHSA-2019:1190