CVE-2018-17205

An issue was discovered in Open vSwitch (OvS) 2.7.x through 2.7.6, affecting ofproto_rule_insert__ in ofproto/ofproto.c. During bundle commit, flows that are added in a bundle are applied to ofproto in order. If a flow cannot be added (e.g., the flow action is a go-to for a group id that does not exist), OvS tries to revert back all previous flows that were successfully applied from the same bundle. This is possible since OvS maintains list of old flows that were replaced by flows from the bundle. While reinserting old flows, OvS has an assertion failure due to a check on rule state != RULE_INITIALIZED. This would work for new flows, but for an old flow the rule state is RULE_REMOVED. The assertion failure causes an OvS crash.

An issue was discovered in Open vSwitch (OvS) 2.7.x through 2.7.6, affecting ofproto_rule_insert__ in ofproto/ofproto.c. During bundle commit, flows that are added in a bundle are applied to ofproto in order. If a flow cannot be added (e.g., the flow action is a go-to for a group id that does not exist), OvS tries to revert back all previous flows that were successfully applied from the same bundle. This is possible since OvS maintains list of old flows that were replaced by flows from the bundle. While reinserting old flows, OvS has an assertion failure due to a check on rule state != RULE_INITIALIZED. This would work for new flows, but for an old flow the rule state is RULE_REMOVED. The assertion failure causes an OvS crash.

Se ha descubierto un problema en Open vSwitch (OvS) en versiones 2.7.x hasta la 2.7.6 que afecta a ofproto_rule_insert__ en ofproto/ofproto.c. Durante el commit bundle, los flujos que se añaden a un bundle se aplican a ofproto en orden. Si un flujo no se puede añadir (por ejemplo, la acción flow es un go-to para un ID de grupo que no existe), OvS intenta revertir todos los flujos anteriores cuando se aplican con éxito desde el mismo bundle. Esto es posible porque OvS mantiene una lista de flujos antiguos que se reemplazaron por flujos del bundle. Cuando se vuelve a insertar flujos antiguos, OvS tiene un fallo de aserción debido a una comprobación en la declaración de regla != RULE_INITIALIZED. Esto funcionaría para los nuevos flujos, pero para un flujo antiguo, la sentencia es RULE_REMOVED. El fallo de aserción provoca el cierre inesperado de OvS.