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A flaw was found in the Linux kernels implementation of IPMI (remote baseband access) where an attacker with local access to read /proc/ioports may be able to create a use-after-free condition when the kernel module is unloaded. The use after-free condition may result in privilege escalation. Investigation is ongoing. Upstream Patch: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=401e7e88d4ef80188ffa07095ac00456f901b8c4
Created kernel tracking bugs for this issue: Affects: fedora-all [bug 1709181]
This was fixed for Fedora with the 5.0.4 stable kernel updates.
Statement: This flaw has been rated as "Moderate" as the attacker needs to be able to abuse this flaw in a very narrow race condition of the kernel module being unloaded. This scoring system from this flaw differentiates from other sources as the attacker must have a local account to be able to read the file (/proc/ioports) while the module is unloaded. None of the above actions are 'network facing' attack vectors.
Mitigation: A mitigation to this flaw would be to no longer use IPMI on affected hardware until the kernel has been updated. Existing systems that have IPMI kernel modules loaded will need to unload the "ipmi_si" kernel module and blacklist ( See https://access.redhat.com/solutions/41278 for a guide on how to blacklist modules). Take careful consideration that if unloading and blacklisting the module, this creates a one-time attack vector window for a local attacker.
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2019:1873 https://access.redhat.com/errata/RHSA-2019:1873
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2019:1891 https://access.redhat.com/errata/RHSA-2019:1891
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-2019-11811
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2019:1959 https://access.redhat.com/errata/RHSA-2019:1959
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2019:1971 https://access.redhat.com/errata/RHSA-2019:1971
This issue has been addressed in the following products: Red Hat Enterprise MRG 2 Via RHSA-2019:4057 https://access.redhat.com/errata/RHSA-2019:4057
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-2019:4058 https://access.redhat.com/errata/RHSA-2019:4058
This issue has been addressed in the following products: Red Hat Enterprise Linux 7.5 Extended Update Support Via RHSA-2020:0036 https://access.redhat.com/errata/RHSA-2020:0036
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2020:2854 https://access.redhat.com/errata/RHSA-2020:2854