RHEL 7 : kernel (RHSA-2019:1485) (SACK Panic) (SACK Slowness)

High Nessus Plugin ID 125973

Synopsis

The remote Red Hat host is missing one or more security updates.

Description

An update for kernel is now available for Red Hat Enterprise Linux 7.2 Advanced Update Support, Red Hat Enterprise Linux 7.2 Telco Extended Update Support, and Red Hat Enterprise Linux 7.2 Update Services for SAP Solutions.

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

Security Fix(es) :

* An integer overflow flaw was found in the way the Linux kernel's networking subsystem processed TCP Selective Acknowledgment (SACK) segments. While processing SACK segments, the Linux kernel's socket buffer (SKB) data structure becomes fragmented. Each fragment is about TCP maximum segment size (MSS) bytes. To efficiently process SACK blocks, the Linux kernel merges multiple fragmented SKBs into one, potentially overflowing the variable holding the number of segments. A remote attacker could use this flaw to crash the Linux kernel by sending a crafted sequence of SACK segments on a TCP connection with small value of TCP MSS, resulting in a denial of service (DoS).
(CVE-2019-11477)

* Kernel: tcp: excessive resource consumption while processing SACK blocks allows remote denial of service (CVE-2019-11478)

* Kernel: tcp: excessive resource consumption for TCP connections with low MSS allows remote denial of service (CVE-2019-11479)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Bug Fix(es) :

* THP: Race between MADV_DONTNEED and NUMA hinting node migration code (BZ# 1698103)

* [RHEL7] md_clear flag missing from /proc/cpuinfo on late microcode update (BZ#1712989)

* [RHEL7] MDS mitigations are not enabled after double microcode update (BZ# 1712994)

* WARNING: CPU: 0 PID: 0 at kernel/jump_label.c:90
__static_key_slow_dec+0xa6 /0xb0 (BZ#1713000)

Solution

Update the affected packages.

See Also

https://access.redhat.com/security/vulnerabilities/tcpsack

https://access.redhat.com/errata/RHSA-2019:1485

https://access.redhat.com/security/cve/cve-2019-11477

https://access.redhat.com/security/cve/cve-2019-11478

https://access.redhat.com/security/cve/cve-2019-11479

Plugin Details

Severity: High

ID: 125973

File Name: redhat-RHSA-2019-1485.nasl

Version: 1.6

Type: local

Agent: unix

Published: 2019/06/18

Updated: 2020/01/10

Dependencies: 12634, 122878

Risk Information

Risk Factor: High

CVSS v2.0

Base Score: 7.8

Temporal Score: 5.8

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C

Temporal Vector: CVSS2#E:U/RL:OF/RC:C

CVSS v3.0

Base Score: 7.5

Temporal Score: 6.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:redhat:enterprise_linux:kernel, p-cpe:/a:redhat:enterprise_linux:kernel-abi-whitelists, p-cpe:/a:redhat:enterprise_linux:kernel-debug, p-cpe:/a:redhat:enterprise_linux:kernel-debug-debuginfo, p-cpe:/a:redhat:enterprise_linux:kernel-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-debuginfo, p-cpe:/a:redhat:enterprise_linux:kernel-debuginfo-common-x86_64, p-cpe:/a:redhat:enterprise_linux:kernel-devel, p-cpe:/a:redhat:enterprise_linux:kernel-doc, p-cpe:/a:redhat:enterprise_linux:kernel-headers, p-cpe:/a:redhat:enterprise_linux:kernel-tools, p-cpe:/a:redhat:enterprise_linux:kernel-tools-debuginfo, p-cpe:/a:redhat:enterprise_linux:kernel-tools-libs, p-cpe:/a:redhat:enterprise_linux:kernel-tools-libs-devel, p-cpe:/a:redhat:enterprise_linux:perf, p-cpe:/a:redhat:enterprise_linux:perf-debuginfo, p-cpe:/a:redhat:enterprise_linux:python-perf, p-cpe:/a:redhat:enterprise_linux:python-perf-debuginfo, cpe:/o:redhat:enterprise_linux:7.2

Required KB Items: Host/local_checks_enabled, Host/RedHat/release, Host/RedHat/rpm-list, Host/cpu

Exploit Ease: No known exploits are available

Patch Publication Date: 2019/06/17

Vulnerability Publication Date: 2019/06/19

Reference Information

CVE: CVE-2019-11477, CVE-2019-11478, CVE-2019-11479

RHSA: 2019:1485