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This bulletin was written by Vigil@nce : http://vigilance.fr/offer

SYNTHESIS OF THE VULNERABILITY

An attacker can rename a directory on a NFS share of FreeBSD, in
order to trigger a denial of service.

Impacted products: FreeBSD

Severity: 2/4

Creation date: 09/04/2014

DESCRIPTION OF THE VULNERABILITY

The FreeBSD product offers a NFS service.

When an authenticated NFS client renames a directory, the
nfsrvd_rename() function uses a lock. However, this lock is taken
in the reverse order. If two renaming operations are performed
simultaneously, a deadlock thus occurs.

An attacker can therefore rename a directory on a NFS share of
FreeBSD, in order to trigger a denial of service.

ACCESS TO THE COMPLETE VIGIL@NCE BULLETIN

http://vigilance.fr/vulnerability/FreeBSD-denial-of-service-via-NFS-Server-14557