CVE-2021-20194

Se presenta una vulnerabilidad en el kernel de Linux versiones superiores a 5.2 (si el kernel compilado con los parámetros config CONFIG_BPF_SYSCALL=y , CONFIG_BPF=y , CONFIG_CGROUPS=y , CONFIG_CGROUP_BPF=y , CONFIG_HARDENED_USERCOPY no se establece y el hook BPF a getsockopt está registrado). Como resultado de la ejecución de BPF, el usuario local puede desencadenar un error en la función __cgroup_bpf_run_filter_getsockopt() que puede conllevar a un desbordamiento de la pila (debido a una copia de usuario no reforzada). El impacto del ataque podría ser la denegación de servicio o posiblemente una escalada de privilegios

A flaw buffer overflow in the Linux kernel BPF subsystem was found in the way user running BPF script calling getsockopt. A local user could use this flaw to crash the system or possibly escalate their privileges on the system.

Loris Reiff discovered that the BPF implementation in the Linux kernel did not properly validate attributes in the getsockopt BPF hook. A local attacker could possibly use this to cause a denial of service. Olivier Benjamin, Norbert Manthey, Martin Mazein, and Jan H. Schoenherr discovered that the Xen paravirtualization backend in the Linux kernel did not properly propagate errors to frontend drivers in some situations. An attacker in a guest VM could possibly use this to cause a denial of service. Various other issues were also addressed.