Bug 1965458 (CVE-2021-33200)

Summary: CVE-2021-33200 kernel: out-of-bounds reads and writes due to enforcing incorrect limits for pointer arithmetic operations by BPF verifier
Product: [Other] Security Response Reporter: Guilherme de Almeida Suckevicz <gsuckevi>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact: Ziqian SUN (Zamir) <zsun>
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: acaringi, adscvr, airlied, alciregi, allarkin, bdettelb, bhu, blc, bmasney, brdeoliv, bskeggs, chwhite, dhoward, dvlasenk, 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, rkeshri, rvrbovsk, steved, swood, tomckay, walters, wcosta, williams, ykopkova
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: kernel 5.13 rc4 Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in kernel/bpf/verifier.c in BPF in the Linux kernel. An incorrect limit is enforced for pointer arithmetic operations which can be abused to perform out-of-bounds reads and writes in kernel memory, leading to local privilege escalation. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
 Story Points: ---
Clone Of: Environment:
Last Closed: 2021-11-09 21:26:01 UTC Type: ---
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: Red Hat1974415, 1965460, Red Hat1972495, Red Hat1972496, Red Hat1973008, Red Hat1973009    
Bug Blocks: Embargoed1965459    

Description Guilherme de Almeida Suckevicz 2021-05-27 18:14:37 UTC 
A flaw was found in kernel/bpf/verifier.c in BPF in the Linux kernel. An incorrect limit is enforced for pointer arithmetic operations which can be abused to perform out-of-bounds reads and writes in kernel memory, leading to local privilege escalation. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

In particular, there is a corner case where the off reg causes a masking direction change, which then results in an incorrect final aux->alu_limit.

Reference:
https://www.openwall.com/lists/oss-security/2021/05/27/1
Comment 1 Guilherme de Almeida Suckevicz 2021-05-27 18:15:41 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1965460]
Comment 15 errata-xmlrpc 2021-11-09 17:23:34 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 18:27:12 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 21:25:56 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-2021-33200