|Summary:||CVE-2014-8133 kernel: x86: espfix(64) bypass via set_thread_area and CLONE_SETTLS|
|Product:||[Other] Security Response||Reporter:||Petr Matousek <pmatouse>|
|Component:||vulnerability||Assignee:||Red Hat Product Security <security-response-team>|
|Status:||CLOSED ERRATA||QA Contact:||Andrej Manduch <amanduch>|
|Version:||unspecified||CC:||agordeev, amanduch, aquini, carnil, dhoward, fhrbata, kernel-mgr, lwang, mguzik, nmurray, pholasek, plougher, rvrbovsk, security-response-team|
|Fixed In Version:||Doc Type:||Bug Fix|
It was found that the espfix functionality could be bypassed by installing a 16-bit RW data segment into GDT instead of LDT (which espfix checks), and using that segment on the stack. A local, unprivileged user could potentially use this flaw to leak kernel stack addresses.
|Last Closed:||2015-07-22 19:29:28 UTC||Type:||---|
|oVirt Team:||---||RHEL 7.3 requirements from Atomic Host:|
|Cloudforms Team:||---||Target Upstream Version:|
|Bug Depends On:||1172798, 1174374|
Description Petr Matousek 2014-12-10 18:48:59 UTC
It was found that espfix funcionality (when returning to userspace with a 16 bit stack, the CPU will not restore the high word(s) of stack pointer for us on executing iret and thus potentially leaks kernel addresses; espfix fixes this) can be bypassed by installing 16-bit RW data segment into GDT instead of LDT (which espfix checks for) and using it for stack. A local unprivileged user could potentially use this flaw to leak kernel stack addresses. Acknowledgements: Red Hat would like to thank Andy Lutomirski for reporting this issue.
Comment 2 Petr Matousek 2014-12-10 18:50:39 UTC
Statement: This issue did not affect the Linux kernel packages as shipped with Red Hat Enterprise Linux 7 and Red Hat Enterprise Linux MRG 2. Red Hat Enterprise Linux 5 is now in Production 3 Phase of the support and maintenance life cycle. This has been rated as having Low security impact and is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.
Comment 5 Petr Matousek 2014-12-15 18:27:30 UTC
Comment 6 Petr Matousek 2014-12-15 18:35:51 UTC
Created kernel tracking bugs for this issue: Affects: fedora-all [bug 1174374]
Comment 7 Fedora Update System 2014-12-21 06:36:32 UTC
kernel-3.17.7-200.fc20 has been pushed to the Fedora 20 stable repository. If problems still persist, please make note of it in this bug report.
Comment 8 Fedora Update System 2014-12-22 02:32:40 UTC
kernel-3.17.7-300.fc21 has been pushed to the Fedora 21 stable repository. If problems still persist, please make note of it in this bug report.