Important: kernel security and bug fix update

Updated kernel packages that fix several security issues and various bugs
are now available for Red Hat Enterprise Linux 4.

This update has been rated as having important security impact by the Red
Hat Security Response Team.

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

These updated packages fix the following security issues:

* a flaw was found in the Intel PRO/1000 network driver in the Linux
kernel. Frames with sizes near the MTU of an interface may be split across
multiple hardware receive descriptors. Receipt of such a frame could leak
through a validation check, leading to a corruption of the length check. A
remote attacker could use this flaw to send a specially-crafted packet that
would cause a denial of service. (CVE-2009-1385, Important)

* the Linux kernel Network File System daemon (nfsd) implementation did not
drop the CAP_MKNOD capability when handling requests from local,
unprivileged users. This flaw could possibly lead to an information leak or
privilege escalation. (CVE-2009-1072, Moderate)

* Frank Filz reported the NFSv4 client was missing a file permission check
for the execute bit in some situations. This could allow local,
unprivileged users to run non-executable files on NFSv4 mounted file
systems. (CVE-2009-1630, Moderate)

* a missing check was found in the hypervisor_callback() function in the
Linux kernel provided by the kernel-xen package. This could cause a denial
of service of a 32-bit guest if an application running in that guest
accesses a certain memory location in the kernel. (CVE-2009-1758, Moderate)

* a flaw was found in the AGPGART driver. The agp_generic_alloc_page() and
agp_generic_alloc_pages() functions did not zero out the memory pages they
allocate, which may later be available to user-space processes. This flaw
could possibly lead to an information leak. (CVE-2009-1192, Low)

These updated packages also fix the following bugs:

* "/proc/[pid]/maps" and "/proc/[pid]/smaps" can only be read by processes
able to use the ptrace() call on a given process; however, certain
information from "/proc/[pid]/stat" and "/proc/[pid]/wchan" could be used
to reconstruct memory maps, making it possible to bypass the Address Space
Layout Randomization (ASLR) security feature. This update addresses this
issue. (BZ#499549)

* in some situations, the link count was not decreased when renaming unused
files on NFS mounted file systems. This may have resulted in poor
performance. With this update, the link count is decreased in these
situations, the same as is done for other file operations, such as unlink
and rmdir. (BZ#501802)

* tcp_ack() cleared the probes_out variable even if there were outstanding
packets. When low TCP keepalive intervals were used, this bug may have
caused problems, such as connections terminating, when using remote tools
such as rsh and rlogin. (BZ#501754)

* off-by-one errors in the time normalization code could have caused
clock_gettime() to return one billion nanoseconds, rather than adding an
extra second. This bug could have caused the name service cache daemon
(nscd) to consume excessive CPU resources. (BZ#501800)

* a system panic could occur when one thread read "/proc/bus/input/devices"
while another was removing a device. With this update, a mutex has been
added to protect the input_dev_list and input_handler_list variables, which
resolves this issue. (BZ#501804)

* using netdump may have caused a kernel deadlock on some systems.
(BZ#504565)

* the file system mask, which lists capabilities for users with a file
system user ID (fsuid) of 0, was missing the CAP_MKNOD and
CAP_LINUX_IMMUTABLE capabilities. This could, potentially, allow users with
an fsuid other than 0 to perform actions on some file system types that
would otherwise be prevented. This update adds these capabilities. (BZ#497269)

All Red Hat Enterprise Linux 4 users should upgrade to these updated
packages, which contain backported patches to resolve these issues. Note:
The system must be rebooted for this update to take effect.

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

This update is available via Red Hat Network. Details on how to use
the Red Hat Network to apply this update are available at
http://kbase.redhat.com/faq/docs/DOC-11259

491572 - CVE-2009-1072 kernel: nfsd should drop CAP_MKNOD for non-root
497020 - CVE-2009-1192 kernel: agp: zero pages before sending to userspace
499549 - kernel: proc: avoid information leaks to non-privileged processes [rhel-4.8.z]
500297 - CVE-2009-1630 kernel: nfs: fix NFS v4 client handling of MAY_EXEC in nfs_permission
500945 - CVE-2009-1758 kernel: xen: local denial of service
501754 - Bug with TCP tcp_ack() [RHEL 4]
501800 - [RHEL4] Nscd consumes many cpu resources ( nearly 100% ) continuously.
501802 - [RHEL 4] inode of the overwritten file will remain in the icache causing performance issues.
501804 - [Stratus 4.9 bug] panic reading /proc/bus/input/devices during input device removal
502981 - CVE-2009-1385 kernel: e1000_clean_rx_irq() denial of service
504565 - e1000e: sporadic hang in netdump

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-1072
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-1192
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-1385
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-1630
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-1758
http://www.redhat.com/security/updates/classification/#important