The kernel packages contain the Linux kernel, the core of any Linux operating system.
These updated packages fix the following security issues:
the absence of a protection mechanism when attempting to access a critical section of code has been found in the Linux kernel open file descriptors control mechanism, fcntl. This could allow a local unprivileged user to simultaneously execute code, which would otherwise be protected against parallel execution. As well, a race condition when handling locks in the Linux kernel fcntl functionality, may have allowed a process belonging to a local unprivileged user to gain re-ordered access to the descriptor table. (CVE-2008-1669, Important)
a possible hypervisor panic was found in the Linux kernel. A privileged user of a fully virtualized guest could initiate a stress-test File Transfer Protocol (FTP) transfer between the guest and the hypervisor, possibly leading to hypervisor panic. (CVE-2008-1619, Important)
the absence of a protection mechanism when attempting to access a critical section of code, as well as a race condition, have been found in the Linux kernel file system event notifier, dnotify. This could allow a local unprivileged user to get inconsistent data, or to send arbitrary signals to arbitrary system processes. (CVE-2008-1375, Important)
Red Hat would like to thank Nick Piggin for responsibly disclosing the following issue:
when accessing kernel memory locations, certain Linux kernel drivers registering a fault handler did not perform required range checks. A local unprivileged user could use this flaw to gain read or write access to arbitrary kernel memory, or possibly cause a kernel crash. (CVE-2008-0007, Important)
the absence of sanity-checks was found in the hypervisor block backend driver, when running 32-bit paravirtualized guests on a 64-bit host. The number of blocks to be processed per one request from guest to host, or vice-versa, was not checked for its maximum value, which could have allowed a local privileged user of the guest operating system to cause a denial of service. (CVE-2007-5498, Important)
it was discovered that the Linux kernel handled string operations in the opposite way to the GNU Compiler Collection (GCC). This could allow a local unprivileged user to cause memory corruption. (CVE-2008-1367, Low)
As well, these updated packages fix the following bugs:
on IBM System z architectures, when running QIOASSIST enabled QDIO devices in an IBM z/VM environment, the output queue stalled under heavy load. This caused network performance to degrade, possibly causing network hangs and outages.
multiple buffer overflows were discovered in the neofb video driver. It was not possible for an unprivileged user to exploit these issues, and as such, they have not been handled as security issues.
when running Microsoft Windows in a HVM, a bug in vmalloc/vfree caused network performance to degrade.
on certain architectures, a bug in the libATA sata_nv driver may have caused infinite reboots, and an "ata1: CPB flags CMD err flags 0x11" error.
repeatedly hot-plugging a PCI Express card may have caused "Bad DLLP" errors.
a NULL pointer dereference in NFS, which may have caused applications to crash, has been resolved.
when attempting to kexec reboot, either manually or via a panic-triggered kdump, the Unisys ES7000/one hanged after rebooting in the new kernel, after printing the "Memory: 32839688k/33685504k available" line.
Red Hat Enterprise Linux 5 users are advised to upgrade to these updated packages, which contain backported patches to resolve these issues.