Synopsis

Important: kernel security and bug fix update

Type/Severity

Security Advisory: Important

Topic

An update for kernel is now available for Red Hat Enterprise Linux 5.9 Long Life.

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.

Description

The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fix(es):

An industry-wide issue was found in the way many modern microprocessor designs have implemented speculative execution of instructions (a commonly used performance optimization). There are three primary variants of the issue which differ in the way the speculative execution can be exploited.

Note: This issue is present in hardware and cannot be fully fixed via software update. The updated kernel packages provide software mitigation for this hardware issue at a cost of potential performance penalty. Please refer to References section for further information about this issue and the performance impact.

In this update mitigations for x86-64 architecture are provided.

• 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)
  
• 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)
  

Red Hat would like to thank Google Project Zero for reporting these issues.

Bug Fix(es):

• Previously, the page table isolation feature was able to modify the kernel Page Global Directory (PGD) entries with the _NX bit even for CPUs without the capability to use the "no execute" (NX) bit technology. Consequently, the page tables got corrupted, and the kernel panicked at the first page-fault occurrence. This update adds the check of CPU capabilities before modifying kernel PGD entries with _NX. As a result, the operating system no longer panics on boot due to corrupted page tables under the described circumstances. (BZ#1538169)
  
• When booting the operating system with the Kernel Page Table Isolation option enabled, the HPET VSYSCALL shadow mapping was not placed correctly. Consequently, the High Precision Event Timer (HPET) feature was not available early enough, and warnings on boot time occurred. This update fixes the placement of HPET VSYSCALL, and the warnings on boot time due to this behavior no longer occur. (BZ#1541281)
  
• Previously, the routine preparing the kexec crashkernel area did not properly clear the page allocated to be kexec's Page Global Directory (PGD). Consequently, the page table isolation shadow mapping routines failed with a warning message when setting up page table entries. With this update, the underlying source code has been fixed to clear the kexec PGD allocated page before setting up its page table entries. As a result, warnings are no longer issued when setting up kexec. (BZ#1541285)
  
• When changing a kernel page mapping from Read Only (RO) to Read Write (RW), the Translation Lookaside Buffer (TLB) entry was previously not updated. Consequently, a protection fault on a write operation occurred, which led to a kernel panic. With this update, the underlying source code has been fixed to handle such kind of fault properly, and the kernel no longer panics in the described situation. (BZ#1541892)

Solution

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.

Affected Products

• Red Hat Enterprise Linux Server - AUS 5.9 x86_64
• Red Hat Enterprise Linux Server - AUS 5.9 ia64
• Red Hat Enterprise Linux Server - AUS 5.9 i386

Fixes

• BZ - 1519778 - CVE-2017-5753 hw: cpu: speculative execution bounds-check bypass
• BZ - 1519781 - CVE-2017-5754 hw: cpu: speculative execution permission faults handling

CVEs

(none)

References

• https://access.redhat.com/security/updates/classification/#important
• https://access.redhat.com/security/vulnerabilities/speculativeexecution
• https://access.redhat.com/security/cve/CVE-2017-5753
• https://access.redhat.com/security/cve/CVE-2017-5754

Red Hat Enterprise Linux Server - AUS 5.9

SRPM
kernel-2.6.18-348.35.1.el5.src.rpm	SHA-256: ca46b99795cea0b92383cc87c3370f3aa2492d8f0c52948b75c4a6fa207739b3
x86_64
kernel-2.6.18-348.35.1.el5.x86_64.rpm	SHA-256: 9c2fa7be56a23a1a8cccda2283b2dbdbc17ab79ca224fdc6e035755a2c47229f
kernel-debug-2.6.18-348.35.1.el5.x86_64.rpm	SHA-256: 3ff2268b083b84ed66ff0255350e55b313aaeade6e8f162ca4a77b332e5870ba
kernel-debug-debuginfo-2.6.18-348.35.1.el5.x86_64.rpm	SHA-256: cf9cfb97ca6cf45dfc65398d1fff4d2b69c23bbf24002174d65680b598db6a0a
kernel-debug-devel-2.6.18-348.35.1.el5.x86_64.rpm	SHA-256: 7bfa3693db631a61992887ca3dc129b3754323247fb1ab6dc728124feba98681
kernel-debuginfo-2.6.18-348.35.1.el5.x86_64.rpm	SHA-256: 211355de37da03279e49d9d08eec699c445324d38015c9093639d5157f80b75b
kernel-debuginfo-common-2.6.18-348.35.1.el5.x86_64.rpm	SHA-256: 505f5a3695a309e2c1d09d5ef552df0d53c0d4a4851e9748492c3963bb884828
kernel-devel-2.6.18-348.35.1.el5.x86_64.rpm	SHA-256: b72d94bb8f570e103702764ed1c7fdf51d9b6568cf31e07f23d24c86ccbffbb7
kernel-doc-2.6.18-348.35.1.el5.noarch.rpm	SHA-256: 9d240be78bafbc5aa035c241a1737062a9bf93008f10e37e353a7bff21eafb8b
kernel-headers-2.6.18-348.35.1.el5.x86_64.rpm	SHA-256: 90ddc85eb56766f6dd3d7d150b50ef93402129f3cb05d828cd31988cdea34757
kernel-xen-2.6.18-348.35.1.el5.x86_64.rpm	SHA-256: 65ca6ade6f045438efcaad983dc302c682b77de17fc338c195da10f25653141f
kernel-xen-debuginfo-2.6.18-348.35.1.el5.x86_64.rpm	SHA-256: c9013d72dfb79c98939824cbdaab676041e8d0aad8b456d52b40bf9cc217e24d
kernel-xen-devel-2.6.18-348.35.1.el5.x86_64.rpm	SHA-256: a6500bb6079c02401721e98d6d9f17d28c57867ed46e73c18cfa9cc1c1cf9b4e
ia64
kernel-2.6.18-348.35.1.el5.ia64.rpm	SHA-256: e2a12dc732454554f16a9e9d884ba909f250eb7d73f6ea32d6685487efd57ad8
kernel-debug-2.6.18-348.35.1.el5.ia64.rpm	SHA-256: 0d95a08443661177fc816c799acb34b7013d700e7d5198c36e4e1660b78ca15c
kernel-debug-debuginfo-2.6.18-348.35.1.el5.ia64.rpm	SHA-256: 165c91d16e1b1a1616a39ce2676050b6064c5f4cc11795cb00ebeed3f2716296
kernel-debug-devel-2.6.18-348.35.1.el5.ia64.rpm	SHA-256: bcb0484c3a133276dae1e027f2e1a97d71c613cbf16dacef72cc46b99381b49b
kernel-debuginfo-2.6.18-348.35.1.el5.ia64.rpm	SHA-256: 2135591ea8a4789af7de3dba1c54c61f1788ac1f61e21e5c41c2427ac4333af9
kernel-debuginfo-common-2.6.18-348.35.1.el5.ia64.rpm	SHA-256: fba0a58298ccde34617735f7fe5cbdfba42c15ddf590185c397b66c3a5ef2c68
kernel-devel-2.6.18-348.35.1.el5.ia64.rpm	SHA-256: 4d412435802fde9be64ec0cee2d71bb025566f3ad1eb91d3aae851ce260f95d2
kernel-doc-2.6.18-348.35.1.el5.noarch.rpm	SHA-256: 9d240be78bafbc5aa035c241a1737062a9bf93008f10e37e353a7bff21eafb8b
kernel-headers-2.6.18-348.35.1.el5.ia64.rpm	SHA-256: e5943ec39841c58115f9b46f212aa713221db6d0ef5a7173e58bbfdf31e64c11
kernel-xen-2.6.18-348.35.1.el5.ia64.rpm	SHA-256: c9a99480655db28670707985c96e1a7bbbe347f39f746ca62579c11c53f7d414
kernel-xen-debuginfo-2.6.18-348.35.1.el5.ia64.rpm	SHA-256: 81d43325c61674f7132b33ca81f05f12e5bf0935cb64dfd1edab6f6b3aefff90
kernel-xen-devel-2.6.18-348.35.1.el5.ia64.rpm	SHA-256: 799aa4fb6afe38e1d812db882e5f3477e8384052590995d26c286a6266232615
i386
kernel-2.6.18-348.35.1.el5.i686.rpm	SHA-256: 3ac32a3f25f7ba60cfeb7aa685ced9ffabe9b98722b3dee6e1bdb30e6943ea00
kernel-PAE-2.6.18-348.35.1.el5.i686.rpm	SHA-256: 69c2530ee152444eb7611b8ef0650963b2175c2ff6029649dec95d81afc310cf
kernel-PAE-debuginfo-2.6.18-348.35.1.el5.i686.rpm	SHA-256: 4b8f3f75066eba08893a8fd115f8430a9e524f261f51ff72f68df433567bf2a7
kernel-PAE-devel-2.6.18-348.35.1.el5.i686.rpm	SHA-256: 5bdc71340ad1daf3a041f3a9f6f12a5adcf426cb14a015062158a8bf648dd9bc
kernel-debug-2.6.18-348.35.1.el5.i686.rpm	SHA-256: 43ee1905fa7052bd239dc0567f6bebab16e3542a52d1504391d9d27fb412b1d4
kernel-debug-debuginfo-2.6.18-348.35.1.el5.i686.rpm	SHA-256: b7ec129d5946c5d1595f18dcf77d6f77d7090b127c423c7215fe4827d9dc8387
kernel-debug-devel-2.6.18-348.35.1.el5.i686.rpm	SHA-256: 7a4bcff31a2789c8ee2941572fd001bc057adb4d3598a868f686c6a3544591ef
kernel-debuginfo-2.6.18-348.35.1.el5.i686.rpm	SHA-256: 7062a6b1052ca19962a7fd108c09fc3d3045dd6ab6d421e046746401fff1f06f
kernel-debuginfo-common-2.6.18-348.35.1.el5.i686.rpm	SHA-256: 7b4a3b5bd09df78696dae553000be7773d80abd90168b6352d8b424382bedfa1
kernel-devel-2.6.18-348.35.1.el5.i686.rpm	SHA-256: 3e07e6ac91ab9da17f92d6f7b3ca579952b0684f34ef11b627840f4cd17915bd
kernel-doc-2.6.18-348.35.1.el5.noarch.rpm	SHA-256: 9d240be78bafbc5aa035c241a1737062a9bf93008f10e37e353a7bff21eafb8b
kernel-headers-2.6.18-348.35.1.el5.i386.rpm	SHA-256: ce2da5fcc478e707df0bda42c11826201850d305f9df500f168f60d028f4169a
kernel-xen-2.6.18-348.35.1.el5.i686.rpm	SHA-256: abaf4b7df8cd5e2efaaa8a0897e6baa79650cded386308017a0e146b881f9c17
kernel-xen-debuginfo-2.6.18-348.35.1.el5.i686.rpm	SHA-256: d8f26627c9a43242cc3dcf4ae7482bbf4fd8acaa2118c6247735ec55ade9c8a4
kernel-xen-devel-2.6.18-348.35.1.el5.i686.rpm	SHA-256: 7b32d33551d5189420ac95a3f423a96a5a158d811b3c2cfe7f728801e9c550f0