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SYNTHESIS OF THE VULNERABILITY

A local attacker can use an ioctl on a FUSE filesystem, in order
to stop the kernel.

Severity: 1/4

Consequences: denial of service of computer

Provenance: user shell

Means of attack: no proof of concept, no attack

Ability of attacker: expert (4/4)

Confidence: confirmed by the editor (5/5)

Diffusion of the vulnerable configuration: high (3/3)

Creation date: 23/12/2009

IMPACTED PRODUCTS

– Linux kernel

DESCRIPTION OF THE VULNERABILITY

FUSE (Filesystem in UserSpacE) can be used by a unprivileged user.

The fuse_ioctl_copy_user() function of the fs/fuse/file.c file
manages memory copies from/to the user space. This function uses
(kmap) a memory page. However, the kunmap() function is called
with an invalid pointer, which stops the kernel.

A local attacker can therefore use an ioctl on a FUSE filesystem,
in order to stop the kernel.

CHARACTERISTICS

Identifiers: 549400, VIGILANCE-VUL-9310

http://vigilance.fr/vulnerability/Linux-kernel-denial-of-service-via-fuse-ioctl-copy-user-9310