Important: kernel security and bug fix update

Updated kernel packages that fix several security issues and several 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.

This update fixes the following security issues:

* the ADDR_COMPAT_LAYOUT and MMAP_PAGE_ZERO flags were not cleared when a
setuid or setgid program was executed. A local, unprivileged user could use
this flaw to bypass the mmap_min_addr protection mechanism and perform a
NULL pointer dereference attack, or bypass the Address Space Layout
Randomization (ASLR) security feature. (CVE-2009-1895, Important)

* it was discovered that, when executing a new process, the clear_child_tid
pointer in the Linux kernel is not cleared. If this pointer points to a
writable portion of the memory of the new program, the kernel could corrupt
four bytes of memory, possibly leading to a local denial of service or
privilege escalation. (CVE-2009-2848, Important)

* Solar Designer reported a missing capability check in the z90crypt driver
in the Linux kernel. This missing check could allow a local user with an
effective user ID (euid) of 0 to bypass intended capability restrictions.
(CVE-2009-1883, Moderate)

* a flaw was found in the way the do_sigaltstack() function in the Linux
kernel copies the stack_t structure to user-space. On 64-bit machines, this
flaw could lead to a four-byte information leak. (CVE-2009-2847, Moderate)

This update also fixes the following bugs:

* the gcc flag "-fno-delete-null-pointer-checks" was added to the kernel
build options. This prevents gcc from optimizing out NULL pointer checks
after the first use of a pointer. NULL pointer bugs are often exploited by
attackers. Keeping these checks is a safety measure. (BZ#517964)

* the Emulex LPFC driver has been updated to version 8.0.16.47, which
fixes a memory leak that caused memory allocation failures and system
hangs. (BZ#513192)

* an error in the MPT Fusion driver makefile caused CSMI ioctls to not
work with Serial Attached SCSI devices. (BZ#516184)

* this update adds the mmap_min_addr tunable and restriction checks to help
prevent unprivileged users from creating new memory mappings below the
minimum address. This can help prevent the exploitation of NULL pointer
deference bugs. Note that mmap_min_addr is set to zero (disabled) by
default for backwards compatibility. (BZ#517904)

* time-outs resulted in I/O errors being logged to "/var/log/messages" when
running "mt erase" on tape drives using certain LSI MegaRAID SAS adapters,
preventing the command from completing. The megaraid_sas driver's timeout
value is now set to the OS layer value. (BZ#517965)

* a locking issue caused the qla2xxx ioctl module to hang after
encountering errors. This locking issue has been corrected. This ioctl
module is used by the QLogic SAN management tools, such as SANsurfer and
scli. (BZ#519428)

* when a RAID 1 array that uses the mptscsi driver and the LSI 1030
controller became degraded, the whole array was detected as being offline,
which could cause kernel panics at boot or data loss. (BZ#517295)

* on 32-bit architectures, if a file was held open and frequently written
for more than 25 days, it was possible that the kernel would stop flushing
those writes to storage. (BZ#515255)

* a memory allocation bug in ib_mthca prevented the driver from loading if
it was loaded with large values for the "num_mpt=" and "num_mtt=" options.
(BZ#518707)

* with this update, get_random_int() is more random and no longer uses a
common seed value, reducing the possibility of predicting the values
returned. (BZ#519692)

* a bug in __ptrace_unlink() caused it to create deadlocked and unkillable
processes. (BZ#519446)

* previously, multiple threads using the fcntl() F_SETLK command to
synchronize file access caused a deadlock in posix_locks_deadlock(). This
could cause a system hang. (BZ#519429)

Users should upgrade to these updated packages, which contain backported
patches to correct these issues. 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

505983 - CVE-2009-1883 kernel: missing capability check in z90crypt
511171 - CVE-2009-1895 kernel: personality: fix PER_CLEAR_ON_SETID
513192 - [Emulex 4.9 bug] DMA zone exhaustion from lpfc driver memory leak
515255 - NFS problems on RHEL 4 where logs show different lengths
515392 - CVE-2009-2847 kernel: information leak in sigaltstack
515423 - CVE-2009-2848 kernel: execve: must clear current->clear_child_tid
516184 - MPT driver CC_CSMI_SAS_GET_CNTLR_CONFIG IOCTL fails [rhel-4.8.z]
517295 - Missing mptscsi RAID1 disk causes kernel panic when rebooted before array rebuild. [rhel-4.8.z]
517904 - kernel: security: implement mmap_min_addr infrastructure [rhel-4.8.z]
517964 - kernel: build with -fno-delete-null-pointer-checks [rhel-4.8.z]
517965 - MegaRAID SAS 1078 tape I/O errors when using mt erase [rhel-4.8.z]
518707 - num_mtt settings of 2097152 fails in RHEL with infiniband HCA [rhel-4.8.z]
519428 - [NetApp 4.8 bug] Issues with "qioctlmod" module on RHEL4.8 hosts with QLogic FC inbox drivers [rhel-4.8.z]
519429 - [RHEL 4] Lookups due to infinite loops in posix_locks_deadlock [rhel-4.8.z]
519446 - kernel: ptrace: don't use REMOVE_LINKS/SET_LINKS for reparenting [rhel-4.9] [rhel-4.8.z]
519692 - kernel: random: make get_random_int() more random [rhel-4.9] [rhel-4.8.z]

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-1883
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-1895
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-2847
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-2848
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-3238
http://www.redhat.com/security/updates/classification/#important