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 6.6 Extended Update Support.
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):
- It was found that the RFC 5961 challenge ACK rate limiting as implemented in the Linux kernel's networking subsystem allowed an off-path attacker to leak certain information about a given connection by creating congestion on the global challenge ACK rate limit counter and then measuring the changes by probing packets. An off-path attacker could use this flaw to either terminate TCP connection and/or inject payload into non-secured TCP connection between two endpoints on the network. (CVE-2016-5696, Important)
Red Hat would like to thank Yue Cao (Cyber Security Group of the CS department of University of California in Riverside) for reporting this issue.
Bug Fix(es):
- Previously, the BUG_ON() signal appeared in the fs_clear_inode() function where the nfs_have_writebacks() function reported a positive value for nfs_inode->npages. As a consequence, a kernel panic occurred. The provided patch performs a serialization by holding the inode i_lock over the check of PagePrivate and locking the request, which fixes this bug. (BZ#1365163)
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 - Extended Update Support 6.6 x86_64
-
Red Hat Enterprise Linux Server - Extended Update Support 6.6 i386
-
Red Hat Enterprise Linux Server - AUS 6.6 x86_64
-
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.6 s390x
-
Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.6 ppc64
-
Red Hat Enterprise Linux EUS Compute Node 6.6 x86_64
-
Red Hat Enterprise Linux Server - TUS 6.6 x86_64
Fixes
- BZ - 1354708 - CVE-2016-5696 kernel: challenge ACK counter information disclosure.
CVEs
References
Vulmon