Bug 1899966 (CVE-2020-27749)

Summary: CVE-2020-27749 grub2: Stack buffer overflow in grub_parser_split_cmdline()
Product: [Other] Security Response Reporter: Marco Benatto <mbenatto>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: bootloader-eng-team, fmartine, jhlavac, lkundrak, pjanda, pjones, rhughes, security-response-team
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: grub 2.06 Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in grub2. Variable names present are expanded in the supplied command line into their corresponding variable contents, using a 1kB stack buffer for temporary storage, without sufficient bounds checking. If the function is called with a command line that references a variable with a sufficiently large payload, it is possible to overflow the stack buffer, corrupt the stack frame and control execution which could also circumvent Secure Boot protections. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
 Story Points: ---
Clone Of: Environment:
Last Closed: 2021-03-03 01:02:04 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: 1913901, 1913902, 1913903, 1913904, 1913905, 1913906, 1913907, 1913908, 1913909, 1913910, 1913911, 1932592, 1932593, 1932594, 1932595, 1932596, 1932597, 1932598, 1932599, 1932600, 1932601, 1932602, 1932603, 1932604, 1932605, 1932606, 1932607, 1932608, 1932609, 1932610, 1932611, 1932612, 1932613, 1932878, 1932879, 1932880, 1932881, 1932882, 1932887, 1934249, 1990891, 1990893, 1990894, 1990895, 1990896, 1990898    
Bug Blocks: 1899965    

Description Marco Benatto 2020-11-20 13:39:58 UTC 
grub_parser_split_cmdline expands variable names present in the supplied command line in to their corresponding variable contents and uses a 1kB
stack buffer for temporary storage without sufficient bounds checking. If the function is called with a command line that references a variable with a sufficiently large payload, it is possible to overflow the stack buffer, corrupt the stack frame and control execution. An attacker may use this to circumvent Secure Boot protections.
Comment 2 Marco Benatto 2020-11-20 15:42:51 UTC 
Acknowledgments:

Name: Chris Coulson (Canonical)
Comment 7 Marco Benatto 2021-03-02 18:39:48 UTC 
Created grub2 tracking bugs for this issue:

Affects: fedora-all [bug 1934249]
Comment 8 errata-xmlrpc 2021-03-02 19:17:04 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.1 Extended Update Support

Via RHSA-2021:0698 https://access.redhat.com/errata/RHSA-2021:0698
Comment 9 errata-xmlrpc 2021-03-02 19:21:20 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:0696 https://access.redhat.com/errata/RHSA-2021:0696
Comment 10 errata-xmlrpc 2021-03-02 19:25:13 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.2 Extended Update Support

Via RHSA-2021:0697 https://access.redhat.com/errata/RHSA-2021:0697
Comment 11 errata-xmlrpc 2021-03-02 19:36:36 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7.3 Advanced Update Support

Via RHSA-2021:0703 https://access.redhat.com/errata/RHSA-2021:0703
Comment 12 errata-xmlrpc 2021-03-02 19:53:45 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7.2 Advanced Update Support

Via RHSA-2021:0704 https://access.redhat.com/errata/RHSA-2021:0704
Comment 13 errata-xmlrpc 2021-03-02 20:09:35 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7.4 Advanced Update Support
  Red Hat Enterprise Linux 7.4 Update Services for SAP Solutions
  Red Hat Enterprise Linux 7.4 Telco Extended Update Support

Via RHSA-2021:0702 https://access.redhat.com/errata/RHSA-2021:0702
Comment 14 errata-xmlrpc 2021-03-02 20:48:01 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2021:0699 https://access.redhat.com/errata/RHSA-2021:0699
Comment 15 errata-xmlrpc 2021-03-02 20:50:36 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7.7 Extended Update Support

Via RHSA-2021:0700 https://access.redhat.com/errata/RHSA-2021:0700
Comment 16 errata-xmlrpc 2021-03-02 21:01:57 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7.6 Extended Update Support

Via RHSA-2021:0701 https://access.redhat.com/errata/RHSA-2021:0701
Comment 17 Product Security DevOps Team 2021-03-03 01:02:04 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-2020-27749
Comment 18 errata-xmlrpc 2021-05-18 14:37:41 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:1734 https://access.redhat.com/errata/RHSA-2021:1734
Comment 19 errata-xmlrpc 2021-06-29 16:26:20 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:2566 https://access.redhat.com/errata/RHSA-2021:2566
Comment 20 errata-xmlrpc 2021-07-20 22:09:10 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.2 Extended Update Support

Via RHSA-2021:2790 https://access.redhat.com/errata/RHSA-2021:2790
Comment 21 errata-xmlrpc 2021-09-28 14:34:41 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.1 Extended Update Support

Via RHSA-2021:3675 https://access.redhat.com/errata/RHSA-2021:3675