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):

• A flaw was found in the way Linux kernel allocates heap memory to build the scattergather list from a fragment list(skb_shinfo(skb)->frag_list) in

the socket buffer(skb_buff). The heap overflow occurred if 'MAX_SKB_FRAGS + 1' parameter and 'NETIF_F_FRAGLIST' feature were used together. A
remote user or process could use this flaw to potentially escalate their privilege on a system. (CVE-2017-7477, Important)

• The NFS2/3 RPC client could send long arguments to the NFS server. These encoded arguments are stored in an array of memory pages, and accessed using pointer variables. Arbitrarily long arguments could make these pointers point outside the array and cause an out-of-bounds memory access. A remote user or program could use this flaw to crash the kernel (denial of service). (CVE-2017-7645, Important)
• The NFSv2 and NFSv3 server implementations in the Linux kernel through 4.10.13 lacked certain checks for the end of a buffer. A remote attacker could trigger a pointer-arithmetic error or possibly cause other unspecified impacts using crafted requests related to fs/nfsd/nfs3xdr.c and fs/nfsd/nfsxdr.c. (CVE-2017-7895, Important)
• The Linux kernel built with the Kernel-based Virtual Machine (CONFIG_KVM) support was vulnerable to an incorrect segment selector(SS) value error. The error could occur while loading values into the SS register in long mode. A user or process inside a guest could use this flaw to crash the guest, resulting in DoS or potentially escalate their privileges inside the guest. (CVE-2017-2583, Moderate)
• A flaw was found in the Linux kernel's handling of packets with the URG flag. Applications using the splice() and tcp_splice_read() functionality could allow a remote attacker to force the kernel to enter a condition in which it could loop indefinitely. (CVE-2017-6214, Moderate)

Red Hat would like to thank Ari Kauppi for reporting CVE-2017-7895 and Xiaohan Zhang (Huawei Inc.) for reporting CVE-2017-2583.

Bug Fix(es):

• Previously, the reserved-pages counter (HugePages_Rsvd) was bigger than the total-pages counter (HugePages_Total) in the /proc/meminfo file, and HugePages_Rsvd underflowed. With this update, the HugeTLB feature of the Linux kernel has been fixed, and HugePages_Rsvd underflow no longer occurs. (BZ#1445184)
• If a directory on a NFS client was modified while being listed, the NFS client could restart the directory listing multiple times. Consequently, the performance of listing the directory was sub-optimal. With this update, the restarting of the directory listing happens less frequently. As a result, the performance of listing the directory while it is being modified has improved. (BZ#1450851)
• The Fibre Channel over Ethernet (FCoE) adapter in some cases failed to reboot. This update fixes the qla2xxx driver, and FCoE adapter now reboots as expected. (BZ#1446246)
• When a VM with Virtual Function I/O (VFIO) device was rebooted, the QEMU process occasionally terminated unexpectedly due to a failed VFIO Direct Memory Access (DMA) map request. This update fixes the vfio driver and QEMU no longer crashes in the described situation. (BZ#1450855)
• When the operating system was booted with the in-box lpfc driver, a kernel panic occurred on the little-endian variant of IBM Power Systems. This update fixes lpfc, and the kernel no longer panics in the described situation. (BZ#1452044)
• When creating or destroying a VM with Virtual Function I/O (VFIO) devices with "Hugepages" feature enabled, errors in Direct Memory Access (DMA) page table entry (PTE) mappings occurred, and QEMU memory usage behaved unpredictably. This update fixes range computation when making room for large pages in Input/Output Memory Management Unit (IOMMU). As a result, errors in DMA PTE mappings no longer occur, and QEMU has a predictable memory usage in the described situation. (BZ#1450856)

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 for x86_64 - Extended Update Support 7.7 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.6 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.5 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.4 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 7.3 x86_64
• Red Hat Enterprise Linux Server - AUS 7.6 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 IBM z Systems - Extended Update Support 7.5 s390x
• Red Hat Enterprise Linux for Power, big endian 7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.7 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.5 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.4 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 7.3 ppc64
• Red Hat Enterprise Linux for Scientific Computing 7 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.7 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.5 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.4 x86_64
• Red Hat Enterprise Linux EUS Compute Node 7.3 x86_64
• Red Hat Enterprise Linux Server - AUS 7.7 x86_64
• Red Hat Enterprise Linux Server - AUS 7.4 x86_64
• Red Hat Enterprise Linux Server - AUS 7.3 x86_64
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.7 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.4 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 7.3 s390x
• Red Hat Enterprise Linux EUS Compute Node 7.6 x86_64
• Red Hat Enterprise Linux for Power, little endian 7 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.7 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.6 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.5 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.4 ppc64le
• Red Hat Enterprise Linux for Power, little endian - Extended Update Support 7.3 ppc64le
• Red Hat Enterprise Linux Server - TUS 7.7 x86_64
• Red Hat Enterprise Linux Server - TUS 7.6 x86_64
• Red Hat Enterprise Linux Server - TUS 7.3 x86_64
• Red Hat Enterprise Linux Server (for IBM Power LE) - Update Services for SAP Solutions 7.7 ppc64le
• Red Hat Enterprise Linux Server (for IBM Power LE) - Update Services for SAP Solutions 7.6 ppc64le
• Red Hat Enterprise Linux Server (for IBM Power LE) - Update Services for SAP Solutions 7.4 ppc64le
• Red Hat Enterprise Linux Server (for IBM Power LE) - Update Services for SAP Solutions 7.3 ppc64le
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.7 x86_64
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.6 x86_64
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.4 x86_64
• Red Hat Enterprise Linux Server - Update Services for SAP Solutions 7.3 x86_64

Fixes

• BZ - 1414735 - CVE-2017-2583 Kernel: Kvm: vmx/svm potential privilege escalation inside guest
• BZ - 1426542 - CVE-2017-6214 kernel: ipv4/tcp: Infinite loop in tcp_splice_read()
• BZ - 1443615 - CVE-2017-7645 kernel: nfsd: Incorrect handling of long RPC replies
• BZ - 1445207 - CVE-2017-7477 kernel: net: Heap overflow in skb_to_sgvec in macsec.c
• BZ - 1446103 - CVE-2017-7895 kernel: NFSv3 server does not properly handle payload bounds checking of WRITE requests

CVEs

• CVE-2017-2583
• CVE-2017-6214
• CVE-2017-7477
• CVE-2017-7645
• CVE-2017-7895

References

• https://access.redhat.com/security/updates/classification/#important
• https://access.redhat.com/articles/3090941