CVE-2014-3532, -3533: two local DoS vulnerabilities in dbus-daemon

[Simon McVittie]

Impact: denial of service (force system services to exit)
Access required: local
Versions affected by CVE-2014-3532: dbus >= 1.3.0 on Linux >= 2.6.37-rc4
Versions affected by CVE-2014-3533: dbus >= 1.3.0 on all Unix platforms

Alban Crequy at Collabora Ltd. discovered a bug in dbus-daemon's support
for file descriptor passing. A malicious process could force system
services or user applications to be disconnected from the D-Bus system
bus by sending them a message containing a file descriptor, then causing
that file descriptor to exceed the kernel's maximum recursion depth
(itself introduced to fix a DoS) before dbus-daemon forwards the message
to the victim process. Most services and applications exit when
disconnected from the system bus, leading to a denial of service. This
is tracked as fd.o#80163 and CVE-2014-3532.

Additionally, Alban discovered that bug fd.o#79694, a bug previously
reported by Alejandro Martínez Suárez which was not believed to be a
security flaw, could be used for a similar denial of service, by causing
dbus-daemon to attempt to forward invalid file descriptors to a victim
process when file descriptors become associated with the wrong message.
Its security implications are tracked as fd.o#80469 and CVE-2014-3533.

For the 1.8.x stable branch, these vulnerabilities are fixed in version
1.8.6. For the 1.6.x old-stable branch, these vulnerabilities are fixed
in version 1.6.22.

All earlier versions of dbus with the file descriptor passing feature
(1.3.0 and up) are believed to be vulnerable. Distributions that
backport security fixes should backport git commits
07f4c12efe3b9bd45d109bc5fbaf6d9dbf69d78e and
9ca90648fc870c24d852ce6d7ce9387a9fc9a94a, attached.

References:

[fd.o#79694] https://bugs.freedesktop.org/show_bug.cgi?id=79694
[fd.o#80469] https://bugs.freedesktop.org/show_bug.cgi?id=80469
[fd.o#80163] https://bugs.freedesktop.org/show_bug.cgi?id=80163

Regards,
    S

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