Red Hat Security Advisory 2012-0571-01 - The kernel packages contain the Linux kernel, the core of any Linux operating system. A flaw was found in the way the Linux kernel's journal_unmap_buffer() function handled buffer head states. On systems that have an ext4 file system with a journal mounted, a local, unprivileged user could use this flaw to cause a denial of service. A flaw was found in the way the KVM_CREATE_IRQCHIP ioctl was handled. Calling this ioctl when at least one virtual CPU already existed could lead to a NULL pointer dereference later when the VCPU is scheduled to run. A local, unprivileged user on a KVM host could use this flaw to crash the host.
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