Scientific Linux Security Update : kernel on SL6.x i386/x86_64

This script is Copyright (C) 2015-2016 Tenable Network Security, Inc.

Synopsis :

The remote Scientific Linux host is missing one or more security

Description :

- A flaw was found in the way the Linux kernel's file
system implementation handled rename operations in which
the source was inside and the destination was outside of
a bind mount. A privileged user inside a container could
use this flaw to escape the bind mount and, potentially,
escalate their privileges on the system. (CVE-2015-2925,

- It was found that the x86 ISA (Instruction Set
Architecture) is prone to a denial of service attack
inside a virtualized environment in the form of an
infinite loop in the microcode due to the way
(sequential) delivering of benign exceptions such as #AC
(alignment check exception) and #DB (debug exception) is
handled. A privileged user inside a guest could use
these flaws to create denial of service conditions on
the host kernel. (CVE-2015-5307, CVE-2015-8104,

- A race condition flaw was found in the way the Linux
kernel's IPC subsystem initialized certain fields in an
IPC object structure that were later used for permission
checking before inserting the object into a globally
visible list. A local, unprivileged user could
potentially use this flaw to elevate their privileges on
the system. (CVE-2015-7613, Important)

- It was found that the Linux kernel's keys subsystem did
not correctly garbage collect uninstantiated keyrings. A
local attacker could use this flaw to crash the system
or, potentially, escalate their privileges on the
system. (CVE-2015-7872, Important)

This update also fixes the following bugs :

- Previously, Human Interface Device (HID) ran a report on
an unaligned buffer, which could cause a page fault
interrupt and an oops when the end of the report was
read. This update fixes this bug by padding the end of
the report with extra bytes, so the reading of the
report never crosses a page boundary. As a result, a
page fault and subsequent oops no longer occur.

- The NFS client was previously failing to detect a
directory loop for some NFS server directory structures.
This failure could cause NFS inodes to remain referenced
after attempting to unmount the file system, leading to
a kernel crash. Loop checks have been added to VFS,
which effectively prevents this problem from occurring.

- Due to a race whereby the nfs_wb_pages_cancel() and
nfs_commit_release_pages() calls both removed a request
from the nfs_inode struct type, the kernel panicked with
negative nfs_inode.npages count. The provided upstream
patch performs the required serialization by holding the
inode i_lock over the check of PagePrivate and locking
the request, thus preventing the race and kernel panic
from occurring.

- Due to incorrect URB_ISO_ASAP semantics, playing an
audio file using a USB sound card could previously fail
for some hardware configurations. This update fixes the
bug, and playing audio from a USB sound card now works
as expected.

- Inside hugetlb, region data structures were protected by
a combination of a memory map semaphore and a single
hugetlb instance mutex. However, a page-fault
scalability improvement backported to the kernel on
previous releases removed the single hugetlb instance
mutex and introduced a new mutex table, making the
locking combination insufficient, leading to possible
race windows that could cause corruption and undefined
behavior. This update fixes the problem by introducing a
required spinlock to the region tracking functions for
proper serialization. The problem only affects software
using huge pages through hugetlb interface.

The system must be rebooted for this update to take effect.

See also :

Solution :

Update the affected packages.

Risk factor :

Medium / CVSS Base Score : 6.9

Family: Scientific Linux Local Security Checks

Nessus Plugin ID: 87403 ()

Bugtraq ID:

CVE ID: CVE-2015-2925

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