CVE-2019-11487

El kernel de Linux, en versiones anteriores a 5.1-rc5, permite el desbordamiento de la cuenta de referencia de página->_refcount, con los consiguientes problemas de uso de memoria después de su liberación, si existen alrededor de 140 GiB de RAM. Esto está relacionado con fs/fuse/dev.c, fs/pipe.c, fs/splice.c, include/linux/mm.h, include/linux/pipe_fs_i.h, kernel/trace/trace.c, mm/gup.c, y mm/hugetlb.c. Puede ocurrir con las peticiones de FUSE.

A flaw was found in the Linux kernel's implementation of the FUSE filesystem, where it allows a page reference counter overflow. If a page reference counter overflows into a negative value, it can be placed back into the "free" list for reuse by other applications. This flaw allows a local attacker who can manipulate memory page reference counters to cause memory corruption and possible privilege escalation by triggering a use-after-free condition.

The current attack requires the system to have approximately 140 GB of RAM for this attack to be performed. It may be possible that the attack can occur with fewer memory requirements.