CVE-2020-12887

Memory leaks were discovered in the CoAP library in Arm Mbed OS 5.15.3 when using the Arm mbed-coap library 5.1.5. The CoAP parser is responsible for parsing received CoAP packets. The function sn_coap_parser_options_parse() parses the CoAP option number field of all options present in the input packet. Each option number is calculated as a sum of the previous option number and a delta of the current option. The delta and the previous option number are expressed as unsigned 16-bit integers. Due to lack of overflow detection, it is possible to craft a packet that wraps the option number around and results in the same option number being processed again in a single packet. Certain options allocate memory by calling a memory allocation function. In the cases of COAP_OPTION_URI_QUERY, COAP_OPTION_URI_PATH, COAP_OPTION_LOCATION_QUERY, and COAP_OPTION_ETAG, there is no check on whether memory has already been allocated, which in conjunction with the option number integer overflow may lead to multiple assignments of allocated memory to a single pointer. This has been demonstrated to lead to memory leak by buffer orphaning. As a result, the memory is never freed.

Memory leaks were discovered in the CoAP library in Arm Mbed OS 5.15.3 when using the Arm mbed-coap library 5.1.5. The CoAP parser is responsible for parsing received CoAP packets. The function sn_coap_parser_options_parse() parses the CoAP option number field of all options present in the input packet. Each option number is calculated as a sum of the previous option number and a delta of the current option. The delta and the previous option number are expressed as unsigned 16-bit integers. Due to lack of overflow detection, it is possible to craft a packet that wraps the option number around and results in the same option number being processed again in a single packet. Certain options allocate memory by calling a memory allocation function. In the cases of COAP_OPTION_URI_QUERY, COAP_OPTION_URI_PATH, COAP_OPTION_LOCATION_QUERY, and COAP_OPTION_ETAG, there is no check on whether memory has already been allocated, which in conjunction with the option number integer overflow may lead to multiple assignments of allocated memory to a single pointer. This has been demonstrated to lead to memory leak by buffer orphaning. As a result, the memory is never freed.

Se detectaron pérdidas de la memoria en la biblioteca CoAP en Arm Mbed OS versión 5.15.3 cuando se usa la biblioteca Arm mbed-coap versión 5.1.5. El analizador CoAP es responsable de analizar los paquetes CoAP recibidos. La función sn_coap_parser_options_parse() analiza el campo CoAP option number de todas las opciones presentes en el paquete de entrada. Cada número de opción es calculado como una suma del número de opción previo y un delta de la opción actual. El delta y el número de opción anterior son expresados como enteros de 16 bits sin signo. Debido a la falta de detección de desbordamiento, es posible crear un paquete que contenga el número de opción y resulte en que el mismo número de opción sea procesado nuevamente en un solo paquete. Determinadas opciones asignan memoria llamando a una función de asignación de memoria. En los casos de COAP_OPTION_URI_QUERY, COAP_OPTION_URI_PATH, COAP_OPTION_LOCATION_QUERY y COAP_OPTION_ETAG, no se comprueba si ya se ha asignado memoria, lo que en conjunto con el desbordamiento de enteros del número de opción puede conllevar a múltiples asignaciones de memoria asignada a un único puntero. Se ha demostrado que esto conlleva a una pérdida de memoria mediante un huérfano de búfer. Como resultado, la memoria nunca es liberada