CVE-2019-15791

In shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, shiftfs_btrfs_ioctl_fd_replace() installs an fd referencing a file from the lower filesystem without taking an additional reference to that file. After the btrfs ioctl completes this fd is closed, which then puts a reference to that file, leading to a refcount underflow.

In shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, shiftfs_btrfs_ioctl_fd_replace() installs an fd referencing a file from the lower filesystem without taking an additional reference to that file. After the btrfs ioctl completes this fd is closed, which then puts a reference to that file, leading to a refcount underflow.

En shiftfs, un parche no upstream para el Kernel de Linux incluido en las series kernel de Ubuntu versiones 5.0 y 5.3, shiftfs_btrfs_ioctl_fd_replace() instala un fd que hace referencia a un archivo del sistema de archivos inferior sin tomar una referencia adicional a ese archivo. Después de que el btrfs ioctl completa este fd se cierra, lo que entonces pone una referencia a ese archivo, lo que lleva a un subflujo de recuento.