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

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


Synopsis :

The remote Scientific Linux host is missing one or more security
updates.

Description :

Two flaws were found in the way the Linux kernel's networking
implementation handled UDP packets with incorrect checksum values. A
remote attacker could potentially use these flaws to trigger an
infinite loop in the kernel, resulting in a denial of service on the
system, or cause a denial of service in applications using the edge
triggered epoll functionality. (CVE-2015-5364, CVE-2015-5366,
Important)

This update also fixes the following bugs :

- When removing a directory, and a reference was held to
that directory by a reference to a negative child
dentry, the directory dentry was previously not killed.
In addition, once the negative child dentry was killed,
an unlinked and unused dentry was present in the cache.
As a consequence, deadlock could be caused by forcing
the dentry eviction while the file system in question
was frozen. With this update, all unused dentries are
unhashed and evicted just after a successful directory
removal, which avoids the deadlock, and the system no
longer hangs in the aforementioned scenario.

- Due to the broken s_umount lock ordering, a race
condition occurred when an unlinked file was closed and
the sync (or syncfs) utility was run at the same time.
As a consequence, deadlock occurred on a frozen file
system between sync and a process trying to unfreeze the
file system. With this update, sync (or syncfs) is
skipped on a frozen file system, and deadlock no longer
occurs in the aforementioned situation.

- Previously, in the scenario when a file was opened by
file handle (fhandle) with its dentry not present in
dcache ('cold dcache') and then making use of the
unlink() and close() functions, the inode was not freed
upon the close() system call. As a consequence, the
iput() final was delayed indefinitely. A patch has been
provided to fix this bug, and the inode is now freed as
expected.

- Due to a corrupted Executable and Linkable Format (ELF)
header in the /proc/vmcore file, the kdump utility
failed to provide any information. The underlying source
code has been patched, and kdump now provides debuging
information for kernel crashes as intended.

- Previously, running the multipath request queue caused
regressions in cases where paths failed regularly under
I/O load. This regression manifested as I/O stalls that
exceeded 300 seconds. This update reverts the changes
aimed to reduce running the multipath request queue
resulting in I/O stalls completing in a timely manner.

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

See also :

http://www.nessus.org/u?e5cd0e07

Solution :

Update the affected packages.

Risk factor :

High / CVSS Base Score : 7.8
(CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C)

Family: Scientific Linux Local Security Checks

Nessus Plugin ID: 85397 ()

Bugtraq ID:

CVE ID: CVE-2015-5364
CVE-2015-5366

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