REDHAT-BUG-832532: Race Condition

Florian Weimer found a local file disclosure flaw in accountsservice, an account management system using D-Bus for querying and manipulating user accounts. The implementation of the SetIconFile method of the org.freedesktop.Accounts.User D-Bus interface can disclose arbitrary files due to a race condition in userchangeiconfileauthorizedcb() in /usr/libexec/accounts-daemon. When this function calls getcalleruid(), it uses PolicyKit to obtain the UID of the requesting process from /proc. At the time the UID is fetched, it may not match the original UID making the D-Bus request if the process has executed an SUID binary.