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Red Hat: RHSA-2019-1602-01 Important: Kernel-Alt DoS Issues

red hat
Calendar Grey June 25, 2019
Dist Redhat Esm H88
Essential kernel-alt security patch for Red Hat Enterprise Linux 7 addresses critical flaws in TCP handling.
An update for kernel-alt is now available for Red Hat Enterprise Linux 7

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.

Summary

The kernel-alt packages provide the Linux kernel version 4.x.
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.

Topics%20covered

Topics Covered

security advisory denial of service Red Hat critical networking tcp kernel-alt

References

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 https://access.redhat.com/security/updates/classification/#important https://access.redhat.com/security/vulnerabilities/tcpsack

Package List

Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7):
Source: kernel-alt-4.14.0-115.8.2.el7a.src.rpm
aarch64: kernel-4.14.0-115.8.2.el7a.aarch64.rpm kernel-debug-4.14.0-115.8.2.el7a.aarch64.rpm kernel-debug-debuginfo-4.14.0-115.8.2.el7a.aarch64.rpm kernel-debug-devel-4.14.0-115.8.2.el7a.aarch64.rpm kernel-debuginfo-4.14.0-115.8.2.el7a.aarch64.rpm kernel-debuginfo-common-aarch64-4.14.0-115.8.2.el7a.aarch64.rpm kernel-devel-4.14.0-115.8.2.el7a.aarch64.rpm kernel-headers-4.14.0-115.8.2.el7a.aarch64.rpm kernel-tools-4.14.0-115.8.2.el7a.aarch64.rpm kernel-tools-debuginfo-4.14.0-115.8.2.el7a.aarch64.rpm kernel-tools-libs-4.14.0-115.8.2.el7a.aarch64.rpm perf-4.14.0-115.8.2.el7a.aarch64.rpm perf-debuginfo-4.14.0-115.8.2.el7a.aarch64.rpm python-perf-4.14.0-115.8.2.el7a.aarch64.rpm python-perf-debuginfo-4.14.0-115.8.2.el7a.aarch64.rpm
noarch: kernel-abi-whitelists-4.14.0-115.8.2.el7a.noarch.rpm kernel-doc-4.14.0-115.8.2.el7a.noarch.rpm
ppc64le: kernel-4.14.0-115.8.2.el7a.ppc64le.rpm kernel-bootwrapper-4.14.0-115.8.2.el7a.ppc64le.rpm kernel-debug-4.14.0-115.8.2.el7a.ppc64le.rpm kernel-debug-debuginfo-4.14.0-115.8.2.el7a.ppc64le.rpm kernel-debuginfo-4.14.0-115.8.2.el7a.ppc64le.rpm kernel-debuginfo-common-ppc64le-4.14.0-115.8.2.el7a.ppc64le.rpm

Read the Full Advisory


Severity
important
Lowest
Low
Medium
High
Critical

Advisory ID: RHSA-2019:1602-01
Product: Red Hat Enterprise Linux
Advisory URL: https://access.redhat.com/errata/RHSA-2019:1602
Issue date: 2019-06-25

Topic

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 impactof Important. A Common Vulnerability Scoring System (CVSS) base score,which gives a detailed severity rating, is available for each vulnerabilityfrom the CVE link(s) in the References section.

Topics%20covered

Topics Covered

security advisory denial of service Red Hat critical networking tcp kernel-alt

Relevant Releases Architectures

Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) - aarch64, noarch, ppc64le, s390x

Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) - aarch64, noarch, ppc64le

Bugs Fixed

1719123 - CVE-2019-11477 Kernel: tcp: integer overflow while processing SACK blocks allows remote denial of service

1719128 - CVE-2019-11478 Kernel: tcp: excessive resource consumption while processing SACK blocks allows remote denial of service

1719129 - CVE-2019-11479 kernel: tcp: excessive resource consumption for TCP connections with low MSS allows remote denial of service

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