Important: kernel-alt security, bug fix, and enhancement update
Security Advisory: Important
An update for kernel-alt is now available for Red Hat Enterprise Linux 7.
Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.
The kernel-alt packages provide the Linux kernel version 4.x.
The following packages have been upgraded to a later upstream version: kernel-alt (4.14.0). (BZ#1492717)
Security Fix(es):
Variant CVE-2017-5715 triggers the speculative execution by utilizing branch target injection. It relies on the presence of a precisely-defined instruction sequence in the privileged code as well as the fact that memory accesses may cause allocation into the microprocessor's data cache even for speculatively executed instructions that never actually commit (retire). As a result, an unprivileged attacker could use this flaw to cross the syscall and guest/host boundaries and read privileged memory by conducting targeted cache side-channel attacks. (CVE-2017-5715, Important, ARM)
Variant CVE-2017-5753 triggers the speculative execution by performing a bounds-check bypass. It relies on the presence of a precisely-defined instruction sequence in the privileged code as well as the fact that memory accesses may cause allocation into the microprocessor's data cache even for speculatively executed instructions that never actually commit (retire). As a result, an unprivileged attacker could use this flaw to cross the syscall boundary and read privileged memory by conducting targeted cache side-channel attacks. (CVE-2017-5753, Important, ARM)
Variant CVE-2017-5754 relies on the fact that, on impacted microprocessors, during speculative execution of instruction permission faults, exception generation triggered by a faulting access is suppressed until the retirement of the whole instruction block. In a combination with the fact that memory accesses may populate the cache even when the block is being dropped and never committed (executed), an unprivileged local attacker could use this flaw to read privileged (kernel space) memory by conducting targeted cache side-channel attacks. (CVE-2017-5754, Important, ARM)
For more details about the security issue(s), including the impact, a CVSS score, and other related information, refer to the CVE page(s) listed in the References section.
Red Hat would like to thank Google Project Zero for reporting CVE-2017-5715, CVE-2017-5753, and CVE-2017-5754; Vitaly Mayatskih for reporting CVE-2017-12190; Kirill Tkhai for reporting CVE-2017-15129; Michael Ellerman, Gustavo Romero, Breno Leitao, Paul Mackerras, and Cyril Bur for reporting CVE-2017-1000255; and Armis Labs for reporting CVE-2017-1000410.
Additional Changes:
See the Red Hat Enterprise Linux 7.5 Release Notes linked from References.
For details on how to apply this update, which includes the changes described in this advisory, refer to:
https://access.redhat.com/articles/11258
The system must be rebooted for this update to take effect.
Vulmon