LSN-0083-1

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LSN-0083-1

Summary: Kernel Live Patch Security Notice

Details: The BPF subsystem in the Linux kernel before 4.17 mishandles situations with a long jump over an instruction sequence where inner instructions require substantial expansions into multiple BPF instructions, leading to an overflow. This affects kernel/bpf/core.c and net/core/filter.c.(CVE-2018-25020) Maxim Levitsky discovered that the KVM hypervisor implementation for AMD processors in the Linux kernel did not properly prevent a guest VM from enabling AVIC in nested guest VMs. An attacker in a guest VM could use this to write to portions of the host's physical memory.(CVE-2021-3653) Nadav Amit discovered that the hugetlb implementation in the Linux kernel did not perform TLB flushes under certain conditions. A local attacker could use this to leak or alter data from other processes that use huge pages.(CVE-2021-4002) Andy Nguyen discovered that the netfilter subsystem in the Linux kernel contained an out-of-bounds write in its setsockopt() implementation. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code.(CVE-2021-22555) It was discovered that the virtual file system implementation in the Linux kernel contained an unsigned to signed integer conversion error. A local attacker could use this to cause a denial of service (system crash) or execute arbitrary code.(CVE-2021-33909)

References: https://ubuntu.com/security/notices/LSN-0083-1, https://ubuntu.com/security/CVE-2018-25020, https://ubuntu.com/security/CVE-2021-3653, https://ubuntu.com/security/CVE-2021-4002, https://ubuntu.com/security/CVE-2021-22555, https://ubuntu.com/security/CVE-2021-33909