Bug 1979664 (CVE-2021-36085) - CVE-2021-36085 libsepol: use-after-free in __cil_verify_classperms()
Summary: CVE-2021-36085 libsepol: use-after-free in __cil_verify_classperms()
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2021-36085
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1979665 1983519 1983520 1983521 1983522 1984148
Blocks: 1979670
TreeView+ depends on / blocked
 
Reported: 2021-07-06 16:51 UTC by Guilherme de Almeida Suckevicz
Modified: 2022-04-17 21:28 UTC (History)
11 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2021-11-10 00:23:22 UTC
Embargoed:

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Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2021:4513 0 None None None 2021-11-09 19:03:31 UTC

Description Guilherme de Almeida Suckevicz 2021-07-06 16:51:58 UTC 
The CIL compiler in SELinux 3.2 has a use-after-free in __cil_verify_classperms (called from __verify_map_perm_classperms and hashtab_map).

References:
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=31124
https://github.com/google/oss-fuzz-vulns/blob/main/vulns/selinux/OSV-2021-421.yaml

Upstream patch:
https://github.com/SELinuxProject/selinux/commit/2d35fcc7e9e976a2346b1de20e54f8663e8a6cba
Comment 1 Guilherme de Almeida Suckevicz 2021-07-06 16:52:23 UTC 
Created libsepol tracking bugs for this issue:

Affects: fedora-all [bug 1979665]
Comment 4 Garrett Tucker 2021-07-26 15:18:21 UTC 
selinux/libsepol is mostly local access and to perform this attack would require local access as compared to network access. An attacker would also require some form of privileges to write the policy file and compile the CIL. The availability impact is also low as this flaw would not cause a system wide or complete lack of availability. Instead the attack would only impact availability of selinux temporarily.
Comment 5 errata-xmlrpc 2021-11-09 19:03:29 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:4513 https://access.redhat.com/errata/RHSA-2021:4513
Comment 6 Product Security DevOps Team 2021-11-10 00:23:20 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-2021-36085
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