10 - RHSA-2015:1030

Problem Description:

Updated kernel packages that fix one security issue and three bugs are now available for Red Hat Enterprise Linux 6.4 Advanced Update Support.

Red Hat Product Security has rated this update as having Important security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.

2. Relevant releases/architectures:

Red Hat Enterprise Linux Server AUS (v. 6.4) - i386, noarch, ppc64, s390x, x86_64 Red Hat Enterprise Linux Server Optional AUS (v. 6.4) - i386, ppc64, s390x, x86_64

3. Description:

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

* A use-after-free flaw was found in the way the Linux kernel's SCTP implementation handled authentication key reference counting during INIT collisions. A remote attacker could use this flaw to crash the system or, potentially, escalate their privileges on the system. (CVE-2015-1421, Important)

This issue was discovered by Sun Baoliang of Red Hat.

This update also fixes the following bugs:

* When ARP is disabled on an interface with an ARP entry for a neighbor host present in the ARP cache, letting the cached entry expire and attempting to communicate with that neighbor host could cause the host MAC address to not be resolved correctly after ARP is enabled again on the interface. With the following workaround, the entry is not expired and the described scenario works correctly:

1) Add the maximum number of ARP entries you expect for your configuration to the proc/sys/net/ipv4/neigh/default/gc_thresh file.

2) Ensure that relevant IP addresses are put in the ARP cache when the system boots, for example by executing the following two commands:

ping [IP address] -c 1 ifconfig ethX -arp

(BZ#1207350)

* Previously, the open() system call in some cases failed with an EBUSY error if the opened file was also being renamed at the same time. With this update, the kernel automatically retries open() when this failure occurs, and if the retry is not successful either, open() now fails with an ESTALE error. (BZ#1207813)

* Previously, a race condition occurred in the build_id_cache__add_s() function, which could truncate system files. A patch has been provided to fix this bug, and system files are no longer truncated in the aforementioned scenario. (BZ#1210591)

All kernel users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect.

4. Solution:

Before applying this update, make sure all previously released errata relevant to your system have been applied.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258

5. Bugs fixed (https://bugzilla.redhat.com/):

1196581 - CVE-2015-1421 kernel: net: slab corruption from use after free on INIT collisions