These updated kernel packages address security vulnerabilites, including two possible data corruption scenarios. In addition, a number of drivers have been updated, improvements made to system performance, and various issues have been resolved.
The Linux kernel handles the basic functions of the operating system. Two potential data corruption scenarios have been identified. These scenarios can occur under heavy, complex I/O loads. The first scenario only occurs while performing memory mapped file I/O, where the file is simultaneously unlinked and the corresponding file blocks reallocated. Furthermore, the memory mapped must be to a partial page at the end of a file on an ext3 file system. As such, CentOS considers this scenario unlikely. The second scenario was exhibited in systems with more than 4 GB of memory with a storage controller capable of block device DMA above 4GB (64-bit DMA). By restricting storage drivers to 32-bit DMA, the problem was resolved. Prior to this errata, the SCSI subsystem was already restricted to 32-bit DMA; this errata extends the restriction to block drivers as well. The change consists of disabling 64-bit DMA in the cciss driver (the HP SA5xxx and SA6xxx RAID controllers). The performance implications of this change to the cciss driver are minimal. In addition, the following security vulnerabilities have been addressed: A flaw was found in several hash table implementations in the kernel networking code. A remote attacker sending packets with carefully chosen, forged source addresses could potentially cause every routing cache entry to be hashed into the same hash chain. As a result, the kernel would use a disproportionate amount of processor time to deal with the new packets, leading to a remote denial-of-service (DoS) attack. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CAN-2003-0244 to this issue. A flaw was also found in the "ioperm" system call, which fails to properly restrict privileges. This flaw can allow an unprivileged local user to gain read and write access to I/O ports on the system. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CAN-2003-0246 to this issue. In addition, the following drivers have been updated to the versions indicated: -aacraid: 0.9.9ac6-TEST -qlogic qla2100, qla2200, qla2300: 6.04.01 -aic7xxx_mod: 6.2.30 and aic79xx: 1.3.4 -ips: v6.00.26 -cpqfc: 2.1.2 -fusion: 2.05.00 -e100: 2.2.21-k1 -e1000: 5.0.43-k1, and added netdump support -natsemi: 1.07+LK1.0.17 -cciss: 2.4.45. -cpqarray: 2.4.26 If the system is configured to use alternate drivers, we recommend applying the kudzu errata RHEA-2003:132 prior to updating the kernel. A number of edge conditions in the virtual memory system have been identified and resolved. These included the elimination of memory allocation failures occuring when the system had not depleted all of the physical memory. This would typically lead to process creation and network driver failures, and general performance degradation. Additional memory reclamation improvements were introduced to further smooth out the natural system performance degradation that occur under memory exhaustion conditions. In addition, the latest summit patches have been included. All users should upgrade to these errata packages, which address these issues.