open-vm-tools: access bypass due to realpath race condition in mount.vmhgfs (aka hgfsmounter)

An issue was discovered in open-vm-tools 2009.03.18-154848. Local users can bypass intended access restrictions on mounting shares via a symlink attack that leverages a realpath race condition in mount.vmhgfs (aka hgfsmounter).

vmware-hgfsmounter in VMware Open Virtual Machine Tools (aka open-vm-tools) 8.4.2-261024 and earlier attempts to append to the /etc/mtab file without first checking whether resource limits would interfere, which allows local users to trigger corruption of this file via a process with a small RLIMIT_FSIZE value, a related issue to CVE-2011-1089.