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. 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. Other vulnerabilities have also been addressed.
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