Topic

An update for kernel-rt 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-rt packages provide the Real Time Linux Kernel, which enables fine-tuning for systems with extremely high determinism requirements.

Security Fix(es):

• Out-of-bounds kernel heap access vulnerability was found in xfrm, kernel's IP framework for transforming packets. An error dealing with netlink messages from an unprivileged user leads to arbitrary read/write and privilege escalation. (CVE-2017-7184, Important)
• A race condition issue leading to a use-after-free flaw was found in the way the raw packet sockets are implemented in the Linux kernel networking subsystem handling synchronization. A local user able to open a raw packet socket (requires the CAP_NET_RAW capability) could use this flaw to elevate their privileges on the system. (CVE-2017-1000111, Important)
• An exploitable memory corruption flaw was found in the Linux kernel. The append path can be erroneously switched from UFO to non-UFO in ip_ufo_append_data() when building an UFO packet with MSG_MORE option. If unprivileged user namespaces are available, this flaw can be exploited to gain root privileges. (CVE-2017-1000112, Important)
• A flaw was found in the Linux networking subsystem where a local attacker with CAP_NET_ADMIN capabilities could cause an out-of-bounds memory access by creating a smaller-than-expected ICMP header and sending to its destination via sendto(). (CVE-2016-8399, Moderate)
• Kernel memory corruption due to a buffer overflow was found in brcmf_cfg80211_mgmt_tx() function in Linux kernels from v3.9-rc1 to v4.13-rc1. The vulnerability can be triggered by sending a crafted NL80211_CMD_FRAME packet via netlink. This flaw is unlikely to be triggered remotely as certain userspace code is needed for this. An unprivileged local user could use this flaw to induce kernel memory corruption on the system, leading to a crash. Due to the nature of the flaw, privilege escalation cannot be fully ruled out, although it is unlikely. (CVE-2017-7541, Moderate)
• An integer overflow vulnerability in ip6_find_1stfragopt() function was found. A local attacker that has privileges (of CAP_NET_RAW) to open raw socket can cause an infinite loop inside the ip6_find_1stfragopt() function. (CVE-2017-7542, Moderate)
• A kernel data leak due to an out-of-bound read was found in the Linux kernel in inet_diag_msg_sctp{,l}addr_fill() and sctp_get_sctp_info() functions present since version 4.7-rc1 through version 4.13. A data leak happens when these functions fill in sockaddr data structures used to export socket's diagnostic information. As a result, up to 100 bytes of the slab data could be leaked to a userspace. (CVE-2017-7558, Moderate)
• The mq_notify function in the Linux kernel through 4.11.9 does not set the sock pointer to NULL upon entry into the retry logic. During a user-space close of a Netlink socket, it allows attackers to possibly cause a situation where a value may be used after being freed (use-after-free) which may lead to memory corruption or other unspecified other impact. (CVE-2017-11176, Moderate)
• A divide-by-zero vulnerability was found in the __tcp_select_window function in the Linux kernel. This can result in a kernel panic causing a local denial of service. (CVE-2017-14106, Moderate)

Red Hat would like to thank Chaitin Security Research Lab for reporting CVE-2017-7184; Willem de Bruijn for reporting CVE-2017-1000111; and Andrey Konovalov for reporting CVE-2017-1000112. The CVE-2017-7558 issue was discovered by Stefano Brivio (Red Hat).

Bug Fix(es):

• The kernel-rt packages have been upgraded to the 3.10.0-693.5.2 source tree, which provides number of bug fixes over the previous version. (BZ#1489084)

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 Real Time 7 x86_64
• Red Hat Enterprise Linux for Real Time for NFV 7 x86_64

Fixes

• BZ - 1403833 - CVE-2016-8399 kernel: net: Out of bounds stack read in memcpy_fromiovec
• BZ - 1435153 - CVE-2017-7184 kernel: Out-of-bounds heap access in xfrm
• BZ - 1470659 - CVE-2017-11176 kernel: Use-after-free in sys_mq_notify()
• BZ - 1473198 - CVE-2017-7541 kernel: Possible heap buffer overflow in brcmf_cfg80211_mgmt_tx()
• BZ - 1473649 - CVE-2017-7542 kernel: Integer overflow in ip6_find_1stfragopt() causes infinite loop
• BZ - 1479304 - CVE-2017-1000111 kernel: Heap out-of-bounds in AF_PACKET sockets
• BZ - 1479307 - CVE-2017-1000112 kernel: Exploitable memory corruption due to UFO to non-UFO path switch
• BZ - 1480266 - CVE-2017-7558 kernel: Out of bounds read in inet_diag_msg_sctp{,l}addr_fill() and sctp_get_sctp_info() in SCTP stack
• BZ - 1487295 - CVE-2017-14106 kernel: Divide-by-zero in __tcp_select_window
• BZ - 1489084 - kernel-rt: update to the RHEL7.4.z batch#2 source tree

CVEs

• CVE-2016-8399
• CVE-2017-1000111
• CVE-2017-1000112
• CVE-2017-11176
• CVE-2017-14106
• CVE-2017-7184
• CVE-2017-7541
• CVE-2017-7542
• CVE-2017-7558

References

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