A vulnerability was found in the Linux kernel. When file permissions are modified via chmod and the user is not in the owning group or capable of CAP_FSETID, the setgid bit is cleared in inode_change_ok(). Setting a POSIX ACL via setxattr sets the filepermissions as well as the new ACL, but doesn't clear the setgid bit in a similar way; this allows to bypass the check in chmod. Suggested upstream patch: http://marc.info/?l=linux-fsdevel&m=147162313630259&w=2 http://www.spinics.net/lists/linux-fsdevel/msg101138.html Upstream commits: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=073931017b49d9458aa351605b43a7e34598caef https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=497de07d89c1410d76a15bec2bb41f24a2a89f31 Previous suggestions: http://www.spinics.net/lists/linux-fsdevel/msg98328.html https://patchwork.kernel.org/patch/9137067/ https://patchwork.kernel.org/patch/9138935/ CVE request+assignment: http://seclists.org/oss-sec/2016/q3/380 http://seclists.org/oss-sec/2016/q3/382
Created kernel tracking bugs for this issue: Affects: fedora-all [bug 1368939]
Acknowledgments: Name: Andreas Gruenbacher (Red Hat), Jan Kara (SUSE)
Statement: This issue affects the Linux kernel packages as shipped with Red Hat Enterprise Linux 5. This has been rated as having Moderate 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/. This issue affects the Linux kernel packages as shipped with Red Hat Enterprise Linux 6, 7 and MRG-2. Future Linux kernel updates for the respective releases might address this issue.
This issue has been addressed in the following products: Red Hat Enterprise Linux 6 Via RHSA-2017:0817 https://rhn.redhat.com/errata/RHSA-2017-0817.html
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2017:2077 https://access.redhat.com/errata/RHSA-2017:2077
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2017:1842 https://access.redhat.com/errata/RHSA-2017:1842
This issue has been addressed in the following products: Red Hat Enterprise MRG 2 Via RHSA-2017:2669 https://access.redhat.com/errata/RHSA-2017:2669