Synopsis: Moderate: kernel security and bug fix update
Advisory ID: SLSA-2013:0847-1
Issue Date: 2013-05-21
CVE Numbers: CVE-2013-0153
This update fixes the following security issue:
* A flaw was found in the way the Xen hypervisor AMD IOMMU driver handled
interrupt remapping entries. By default, a single interrupt remapping
table is used, and old interrupt remapping entries are not cleared,
potentially allowing a privileged guest user in a guest that has a passed-
through, bus-mastering capable PCI device to inject interrupt entries into
others guests, including the privileged management domain (Dom0), leading
to a denial of service. (CVE-2013-0153, Moderate)
This update also fixes the following bugs:
* When a process is opening a file over NFSv4, sometimes an OPEN call can
succeed while the following GETATTR operation fails with an NFS4ERR_DELAY
error. The NFSv4 code did not handle such a situation correctly and
allowed an NFSv4 client to attempt to use the buffer that should contain
the GETATTR information. However, the buffer did not contain the valid
GETATTR information, which caused the client to return a “-ENOTDIR” error.
Consequently, the process failed to open the requested file. This update
backports a patch that adds a test condition verifying validity of the
GETATTR information. If the GETATTR information is invalid, it is obtained
later and the process opens the requested file as expected.
* Previously, the xdr routines in NFS version 2 and 3 conditionally
updated the res->count variable. Read retry attempts after a short NFS
read() call could fail to update the res->count variable, resulting in
truncated read data being returned. With this update, the res->count
variable is updated unconditionally so this bug can no longer occur.
* When handling requests from Intelligent Platform Management Interface
(IPMI) clients, the IPMI driver previously used two different locks for an
IPMI request. If two IPMI clients sent their requests at the same time,
each request could receive one of the locks and then wait for the second
lock to become available. This resulted in a deadlock situation and the
system became unresponsive. The problem could occur more likely in
environments with many IPMI clients. This update modifies the IPMI driver
to handle the received messages using tasklets so the driver now uses a
safe locking technique when handling IPMI requests and the mentioned
deadlock can no longer occur.
* Incorrect locking around the cl_state_owners list could cause the NFSv4
state reclaimer thread to enter an infinite loop while holding the Big
Kernel Lock (BLK). As a consequence, the NFSv4 client became unresponsive.
With this update, safe list iteration is used, which prevents the NFSv4
client from hanging in this scenario.
The system must be rebooted for this update to take effect.
– Scientific Linux Development Team