7.2 - RHSA-2015:1042

Problem Description:

Updated kernel packages that fix one security issue and several bugs are now available for Red Hat Enterprise Linux 5.

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 (v. 5 server) - i386, ia64, noarch, ppc, s390x, x86_64 Red Hat Enterprise Linux Desktop (v. 5 client) - i386, noarch, x86_64

3. Description:

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

* It was found that the Linux kernel's implementation of vectored pipe read and write functionality did not take into account the I/O vectors that were already processed when retrying after a failed atomic access operation, potentially resulting in memory corruption due to an I/O vector array overrun. A local, unprivileged user could use this flaw to crash the system or, potentially, escalate their privileges on the system. (CVE-2015-1805, Important)

The security impact of this issue was discovered by Red Hat.

This update fixes the following bugs:

* Due to a bug in the lpfc_device_reset_handler() function, a scsi command timeout could lead to a system crash. With this update, lpfc_device_reset_handler recovers storage without crashing. (BZ#1070964)

* Due to the code decrementing the reclaim_in_progress counter without having incremented it first, severe spinlock contention occurred in the shrink_zone() function even though the vm.max_reclaims_in_progress feature was set to 1. This update provides a patch fixing the underlying source code, and spinlock contention no longer occurs in this scenario. (BZ#1164105)

* A TCP socket using SACK that had a retransmission but recovered from it, failed to reset the retransmission timestamp. As a consequence, on certain connections, if a packet had to be re-transmitted, the retrans_stamp variable was only cleared when the next acked packet was received. This could lead to an early abortion of the TCP connection if this next packet also got lost. With this update, the socket clears retrans_stamp when the recovery is completed, thus fixing the bug. (BZ#1205521)

* Previously, the signal delivery paths did not clear the TS_USEDFPU flag, which could cause problems in the switch_to() function and lead to floating-point unit (FPU) corruption. With this update, TS_USEDFPU is cleared as expected, and FPU is no longer under threat of corruption. (BZ#1193505)

* A race condition in the exit_sem() function previously caused the semaphore undo list corruption. As a consequence, a kernel crash could occur. The corruption in the semaphore undo list has been fixed, and the kernel no longer crashes in this situation. (BZ#1124574)

* Previously, when running the "virsh blockresize [Device] [Newsize]" command to resize the disk, the new size was not reflected in a Red Hat Enterprise Linux 5 Virtual Machine (VM). With this update, the new size is now reflected online immediately in a Red Hat Enterprise Linux 5 VM so it is no longer necessary to reboot the VM to see the new disk size. (BZ#1200855)

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/):

1202855 - CVE-2015-1805 kernel: pipe: iovec overrun leading to memory corruption