Important: kernel security, bug fix, and enhancement update

Topic

An update for kernel is now available for Red Hat Enterprise Linux 7.

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):

• kernel: use-after-free in RDMA listen() (CVE-2021-4028)
• kernel: fget: check that the fd still exists after getting a ref to it (CVE-2021-4083)

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):

• Adding new kernel entry in grub configuration file only after generation of new initramfs (BZ#1893756)
• Cannot mount DFS shares on RHEL7 (BZ#1937304)
• RHEL7.9 - zcrypt DD: Toleration for new IBM Z Crypto Hardware (BZ#1997156)
• kernel panic at skb_free_datagram_locked on 3.10.0-1160.45.1.el7 (BZ#2028740)
• Lots of tasks are getting stuck in I/O wait waiting on the buffer_head locked by the task that is busy shrinking slab for freeing pages - 3 patches to fs/buffer.c (BZ#2030609)
• [RHEL 7.9 Bug] x86/platform/uv: Add more to secondary CPU kdump info (BZ#2042462)
• REGRESSION System panicking in __kmalloc+0x94 from a freelist issue introduced by a block patch. (BZ#2054743)

Enhancement(s):

• RHEL7.9 - kernel: Add support for CPU-MF counter second version 7 (BZ#2048920)

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 7 x86_64
• Red Hat Enterprise Linux Workstation 7 x86_64
• Red Hat Enterprise Linux Desktop 7 x86_64
• Red Hat Enterprise Linux for IBM z Systems 7 s390x
• Red Hat Enterprise Linux for Power, big endian 7 ppc64
• Red Hat Enterprise Linux for Scientific Computing 7 x86_64
• Red Hat Enterprise Linux for Power, little endian 7 ppc64le
• Red Hat Virtualization Host 4 for RHEL 7 x86_64

Fixes

• BZ - 2027201 - CVE-2021-4028 kernel: use-after-free in RDMA listen()
• BZ - 2029923 - CVE-2021-4083 kernel: fget: check that the fd still exists after getting a ref to it

CVEs

• CVE-2021-4028
• CVE-2021-4083

References

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