Red Hat Security Advisory: kernel-alt security, bug fix, and enhancement update

Important

An industry-wide issue was found in the way many modern microprocessor designs have implemented speculative execution of instructions (a commonly used performance optimization). There are three primary variants of the issue which differ in the way the speculative execution can be exploited. Variant CVE-2017-5753 triggers the speculative execution by performing a bounds-check bypass. It relies on the presence of a precisely-defined instruction sequence in the privileged code as well as the fact that memory accesses may cause allocation into the microprocessor's data cache even for speculatively executed instructions that never actually commit (retire). As a result, an unprivileged attacker could use this flaw to cross the syscall boundary and read privileged memory by conducting targeted cache side-channel attacks.

CWE-200 - Exposure of Sensitive Information to an Unauthorized Actor

Buffer overflow in the mp_override_legacy_irq() function in arch/x86/kernel/acpi/boot.c in the Linux kernel through 4.12.2 allows local users to gain privileges via a crafted ACPI table.

CWE-787 - Out-of-bounds Write

It was found that in the Linux kernel through v4.14-rc5, bio_map_user_iov() and bio_unmap_user() in 'block/bio.c' do unbalanced pages refcounting if IO vector has small consecutive buffers belonging to the same page. bio_add_pc_page() merges them into one, but the page reference is never dropped, causing a memory leak and possible system lockup due to out-of-memory condition.

CWE-400 - Uncontrolled Resource Consumption

A vulnerability was found in the Key Management sub component of the Linux kernel, where when trying to issue a KEYTCL_READ on a negative key would lead to a NULL pointer dereference. A local attacker could use this flaw to crash the kernel.

CWE-476 - NULL Pointer Dereference

A use-after-free vulnerability was found in a network namespaces code affecting the Linux kernel since v4.0-rc1 through v4.15-rc5. The function get_net_ns_by_id() does not check for the net::count value after it has found a peer network in netns_ids idr which could lead to double free and memory corruption. This vulnerability could allow an unprivileged local user to induce kernel memory corruption on the system, leading to a crash. Due to the nature of the flaw, privilege escalation cannot be fully ruled out, although it is thought to be unlikely.

CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

A vulnerability was found in the key management subsystem of the Linux kernel. An update on an uninstantiated key could cause a kernel panic, leading to denial of service (DoS).

CWE-476 - NULL Pointer Dereference

The kvm_vm_ioctl_check_extension function in arch/powerpc/kvm/powerpc.c in the Linux kernel before 4.13.11 allows local users to cause a denial of service (NULL pointer dereference and system crash) via a KVM_CHECK_EXTENSION KVM_CAP_PPC_HTM ioctl call to /dev/kvm.

CWE-476 - NULL Pointer Dereference

The Linux kernel is vulerable to a use-after-free flaw when Transformation User configuration interface(CONFIG_XFRM_USER) compile-time configuration were enabled. This vulnerability occurs while closing a xfrm netlink socket in xfrm_dump_policy_done. A user/process could abuse this flaw to potentially escalate their privileges on a system.

CWE-416 - Use After Free