CVE-2021-20239

Se encontró un fallo en el kernel de Linux en versiones anteriores a 5.4.92 en el protocolo BPF. Este fallo permite a un atacante con una cuenta local filtrar información sobre las direcciones internas del kernel. La mayor amenaza de esta vulnerabilidad es la confidencialidad

A flaw was found in the BPF protocol. This flaw allows an attacker with a local account to leak information about kernel internal addresses. The highest threat from this vulnerability is to confidentiality.

Ryota Shiga discovered that the sockopt BPF hooks in the Linux kernel could allow a user space program to probe for valid kernel addresses. A local attacker could use this to ease exploitation of another kernel vulnerability. It was discovered that the BPF verifier in the Linux kernel did not properly handle signed add32 and sub integer overflows. A local attacker could use this to cause a denial of service or possibly execute arbitrary code. Various other issues were also addressed.