CVE-2016-4913

La función get_rock_ridge_filename en fs/isofs/rock.c en el kernel de Linux en versiones anteriores a 4.5.5 no maneja correctamente entradas NM (también conocidas como alternate name) que contienen caracteres \0, lo que permite a usuarios locales obtener información sensible del kernel de memoria o posiblemente tener otro impacto no especificado a través de un sistema de archivo isofs manipulado.

A vulnerability was found in the Linux kernel. Payloads of NM entries are not supposed to contain NUL. When such entry is processed, only the part prior to the first NUL goes into the concatenation (i.e. the directory entry name being encoded by a bunch of NM entries). The process stops when the amount collected so far + the claimed amount in the current NM entry exceed 254. However, the value returned as the total length is the sum of *claimed* sizes, not the actual amount collected. And that's what will be passed to readdir() callback as the name length - 8Kb __copy_to_user() from a buffer allocated by __get_free_page().