RHSA-2019:0202 - Security Advisory

Topic

An update for kernel is now available for Red Hat Enterprise Linux 7.5 Extended Update Support.

Red Hat Product Security has rated this update as having a security impact of Moderate. 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):

• kernel: userfaultfd bypasses tmpfs file permissions (CVE-2018-18397)

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.

Bug Fix(es):

• When applying two instances of the kprobe debugging mechanism to the same function, one of the kprobes in some cases failed, depending on the kernel address space layout. Consequently, a kprobe registration error occurred. This update fixes the bug in the kprobes registration code to properly detect and handle ftrace-based kprobes. As a result, both kprobes now apply successfully in the described scenario. (BZ#1647815)
• Under heavy mad packet load, the SELinux checks in the mad packet queries for InfiniBand (IB) fabrics significantly increased the mad packet execution time. Consequently, if a single machine was executing a large perfquery to the IB switches of a High Performance (HPC) fabric, mad_rpc timeouts occurred, and the query failed even with SELinux disabled. This update eliminates the SELinux checks when SELinux is disabled. As a result, the mad packet queries through perfquery now have their original run times when SELinux is disabled. (BZ#1648810)
• Previously, a file-system shutdown process caused by an I/O error could race against a running fstrim process to acquire a xfs buffer lock. Consequently, the file-system shutdown process never completed due to a deadlock and the file-system became unresponsive, unable to be unmounted. This update fixes the lock ordering so that the deadlock no longer occurs and the file-system shutdown process now completes in the described scenario. (BZ#1657142)

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 for x86_64 - Extended Update Support 7.5 x86_64
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.5 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.5 ppc64
• Red Hat Enterprise Linux EUS Compute Node 7.5 x86_64
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.5 ppc64le

Fixes

• BZ - 1641548 - CVE-2018-18397 kernel: userfaultfd bypasses tmpfs file permissions

CVEs

• CVE-2018-18397

References

• https://access.redhat.com/security/updates/classification/#moderate