Denial of service - CPU loop and memory allocation.

Description

All current released versions of Samba are vulnerable to a denial of
service on an authenticated or guest connection. A malformed packet
can cause the smbd server to loop the CPU performing memory
allocations and preventing any further service.

A connection to a file share, or a local account is needed to exploit
this problem, either authenticated or unauthenticated if guest
connections are allowed.

This flaw is not exploitable beyond causing the code to loop
allocating memory, which may cause the machine to exceed memory
limits.

Patch Availability

A patch addressing this defect has been posted to

http://www.samba.org/samba/security/

Additionally, Samba 3.5.22, 3.6.17 and 4.0.8 have been issued as
security releases to correct the defect. Patches against older Samba
versions are available at http://samba.org/samba/patches/. Samba
vendors and administrators running affected versions are advised to
upgrade or apply the patch as soon as possible.

Workaround

None.

Credits

This problem was found by an internal audit of the Samba code by
Jeremy Allison of Google.