Bug 1976946 (CVE-2021-3635)

Summary: CVE-2021-3635 kernel: flowtable list del corruption with kernel BUG at lib/list_debug.c:50
Product: [Other] Security Response Reporter: Pedro Sampaio <psampaio>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: acaringi, adscvr, airlied, alciregi, bdettelb, bhu, blc, brdeoliv, bskeggs, carnil, chwhite, crwood, dhoward, dvlasenk, egarver, fhrbata, fpacheco, hdegoede, hkrzesin, jarod, jarodwilson, jeremy, jforbes, jlelli, jonathan, josef, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, mlangsdo, nmurray, ptalbert, qzhao, rvrbovsk, security-response-team, steved, tomckay, tuxmealux+redhatbz, walters, wcosta, williams, wmealing, yiche
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: kernel 5.5-rc7 Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in the Linux kernel netfilter implementation. A user with root (CAP_SYS_ADMIN) access is able to panic the system when issuing netfilter netflow commands
Story Points: ---
Clone Of: Environment:
Last Closed: 2021-11-09 21:52:12 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: 1977137, 1977138, 1990729    
Bug Blocks: 1974858, 1978820    

Description Pedro Sampaio 2021-06-28 15:49:51 UTC
A flaw was found in the Linux kernels netfilter implementation. A missing generation check during DELTABLE processing causes it to queue the DELFLOWTABLE operation a second time possibly leading to data corruption and denial of service.  An attacker must have either root or CAP_SYS_ADMIN capabilities to exploit this flaw.

References:

https://bugzilla.redhat.com/show_bug.cgi?id=1974543

Comment 2 Wade Mealing 2021-06-29 04:07:16 UTC
This is rated as a Low, as you must be root or cap_sys_admin with a local account to be able to create the exploitable condition.

Comment 8 Wade Mealing 2021-08-06 05:10:29 UTC
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1990729]

Comment 9 Gianluca Gabrielli 2021-08-27 12:41:40 UTC
Hi folks,

could you please open 1974543 to the public? I cannot find details about this bug anywhere.

Thanks

Comment 10 Salvatore Bonaccorso 2021-09-12 19:03:25 UTC
Hi Gianluca,

(In reply to Gianluca Gabrielli from comment #9)
> Hi folks,
> 
> could you please open 1974543 to the public? I cannot find details about
> this bug anywhere.
> 
> Thanks

External to Red Hat here, but was searching as well for some information about this CVE. I suspect this is about the upstream commit https://git.kernel.org/linus/335178d5429c4cee61b58f4ac80688f556630818


Regards,
Salvatore

Comment 11 Wade Mealing 2021-09-13 02:48:44 UTC
The BZ #1974543 is an internal tracking bug, and contains no information relevant to this flaw.

Comment 13 Gianluca Gabrielli 2021-09-16 12:51:29 UTC
(In reply to Salvatore Bonaccorso from comment #10)
> Hi Gianluca,
> 
> (In reply to Gianluca Gabrielli from comment #9)
> > Hi folks,
> > 
> > could you please open 1974543 to the public? I cannot find details about
> > this bug anywhere.
> > 
> > Thanks
> 
> External to Red Hat here, but was searching as well for some information
> about this CVE. I suspect this is about the upstream commit
> https://git.kernel.org/linus/335178d5429c4cee61b58f4ac80688f556630818

Yes, it really seems the right one. Nice catch and thanks for having shared it.

Comment 14 Justin M. Forbes 2021-11-05 15:58:42 UTC
This was fixed for Fedora with the 5.4.14 stable kernel updates.

Comment 15 errata-xmlrpc 2021-11-09 17:23:48 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:4140 https://access.redhat.com/errata/RHSA-2021:4140

Comment 16 errata-xmlrpc 2021-11-09 18:27:41 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:4356 https://access.redhat.com/errata/RHSA-2021:4356

Comment 17 Product Security DevOps Team 2021-11-09 21:52:08 UTC
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2021-3635