Description of problem:
CIFS has the ability to chase MS-DFS referrals. In order to do this it has to be able to resolve hostnames into IP addresses. For this, it uses the keys API to upcall to the cifs.upcall userspace helper. It then resolves the name and hands the address back to the kernel.
The dns_resolver upcall currently used by CIFS is susceptible to cache stuffing. It's possible for a malicious user to stuff the keyring with the results of a lookup, and then trick the server into mounting a server of his choosing.
This issue did not affect the versions of the Linux kernel as shipped with Red Hat Enterprise Linux 3, 4, and Red Hat Enterprise MRG as they did not include support for the upcall mechanism for the Common Internet File System (CIFS). This issue was addressed in Red Hat Enterprise Linux 5 via https://rhn.redhat.com/errata/RHSA-2010-0723.html.
Fixed upstream in 2.6.35, 126.96.36.199, 188.8.131.52 and 184.108.40.206
kernel-220.127.116.11-150.fc12 has been pushed to the Fedora 12 stable repository. If problems still persist, please make note of it in this bug report.
kernel-18.104.22.168-147.2.4.fc13 has been pushed to the Fedora 13 stable repository. If problems still persist, please make note of it in this bug report.
Introduced via commit 6103335de8afa5d780dcd512abe85c696af7b040 (2.6.25-rc1).
This issue has been addressed in following products:
Red Hat Enterprise Linux 5
Via RHSA-2010:0610 https://rhn.redhat.com/errata/RHSA-2010-0610.html