RHSA-2018:1737 Important: kernel security and bug fix update

Updated

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

Red Hat Product Security has rated this update as having Important security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

Security Fixes are described in RHSA-2018:1737.

This update also fixes the following bugs:

  • Previously, removing a physical CPU from a running system triggered a redundant warning message. This update prevents resetting the processor id value during removal. As a result the warning message no longer appears. (This content is not included.BZ#1563089)

  • This update provides support for enabling or disabling the Return from Interrupt (RFI) flush functionality on IBM POWER Systems with up-to-date firmware. In certain secured environments, a system administrator prefers the system performance to its security. As a result, disabling RFI allows to choose higher system performance over its security. (This content is not included.BZ#1563094)

  • When accepting the Stream Control Transmission Protocol (SCTP) connection, its Transmission Control Block (TCB) migration did not set the data owner as a new socket. As a consequence, it was impossible to release the new socket, and the previous socket experienced a memory leak. This update sets the data owner as a new socket during the SCTP TCB migration. As a result, the new socket no longer underflows, and the memory leak on the previous socket no longer occurs during the described scenario. (This content is not included.BZ#1565981)

  • When the system was under a heavy load, the TX driver in some cases became unresponsive and TCP performed poorly. As a consequence, TX became unresponsive and TCP performed poorly. This update prevents the race condition in the TX driver code and sets the VMXNET 3 internal LRO flag properly. As a result, TX does not become unresponsive and TCP performs as expected under the heavy load. (This content is not included.BZ#1567766)

  • Previously, the UEFI top-level page table was not configured properly to work with the page table isolation (PTI) feature. As a consequence, certain memory locations got corrupted and page tables were set incorrectly, which caused random crashes or system reboots without any error message. With this update, the UEFI top-level page table has been modified to reflect the PTI requirement. As a result, the described problems no longer occur. (This content is not included.BZ#1567892)

  • When a CPU thread went into an idle state, the Indirect Branch Restricted Speculation (IBRS) feature remained enabled on the core. As a consequence, the performance of the idle CPU's sibling decreased. This update disables IBRS before the CPU enters the idle state. As a result, the idle CPU thread no longer decreases the performance of its sibling. (This content is not included.BZ#1570530)

  • Previously, an erroneous code in the x86 kexec system call path caused a memory corruption. As a consequence, the system became unresponsive with the following kernel stack trace:

WARNING: CPU: 13 PID: 36409 at lib/list_debug.c:59 __list_del_entry+0xa1/0xd0 list_del corruption. prev->next should be ffffdd03fddeeca0, but was (null)

This update ensures that the code does not corrupt memory. As a result, the operating system no longer hangs. (This content is not included.BZ#1573169)

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