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.

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):

• 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)

Red Hat would like to thank Ari Kauppi for reporting this issue.

Bug Fix(es):

• If several file operations were started after a mounted NFS share had got idle and its Transmission Control Protocol (TCP) connection had therefore been terminated, these operations could cause multiple TCP SYN packets coming from the NFS client instead of one. With this update, the reconnection logic has been fixed, and only one TCP SYN packet is now sent in the described situation. (BZ#1450850)
• When the ixgbe driver was loaded for a backplane-connected network card, a kernel panic could occur, because the ops.setup_fc function pointer was used before the initialization. With this update, ops.setup_fc is initialized earlier. As a result, ixgbe no longer panics on load. (BZ#1457347)
• When setting an Access Control List (ACL) with 190 and more Access Control Entries (ACEs) on a NFSv4 directory, a kernel crash could previously occur. This update fixes the nfs4_getfacl() function, and the kernel no longer crashes under the described circumstances. (BZ#1449096)
• When upgrading to kernel with the fix for stack guard flaw, a crash could occur in Java Virtual Machine (JVM) environments, which attempted to implement their own stack guard page. With this update, the underlying source code has been fixed to consider the PROT_NONE mapping as a part of the stack, and the crash in JVM no longer occurs under the described circumstances. (BZ#1466667)
• When a program receives IPv6 packets using the raw socket, the ioctl(FIONREAD) and ioctl(SIOCINQ) functions can incorrectly return zero waiting bytes. This update fixes the ip6_input_finish() function to check the raw payload size properly. As a result, the ioctl() function now returns bytes waiting in the raw socket correctly. (BZ#1450870)
• Previously, listing a directory on a non-standard XFS filesystem (with non-default multi-fsb directory blocks) could lead to a soft lock up due to array index overrun in the xfs_dir2_leaf_readbuf() function. This update fixes xfs_dir2_leaf_readbuf(), and the soft lock up no longer occurs under the described circumstances. (BZ#1445179)
• Previously, aborts from the array after the Storage Area Network (SAN) fabric back-pressure led to premature reuse of still valid sequence with the same OX_ID. Consequently, an error message and data corruption could occur. This update fixes the libfc driver to isolate the timed out OX_IDs, thus fixing this bug. (BZ#1455550)
• Previously, a kernel panic occurred when the mcelog daemon executed a huge page memory offline. This update fixes the HugeTLB feature of the Linux kernel to check for the Page Table Entry (PTE) NULL pointer in the page_check_address() function. As a result, the kernel panic no longer occurs under the described circumstances. (BZ#1444351)

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 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 1446103 - CVE-2017-7895 kernel: NFSv3 server does not properly handle payload bounds checking of WRITE requests

CVEs

• CVE-2017-7895

References