The cifs code will attempt to open files on lookup under certain circumstances. What happens though if we find that the file we opened was actually a FIFO or other special file? Currently, the open filehandle just ends up being leaked leading to a dentry refcount mismatch and oops on umount.
An user with access to samba share could use this flaw to crash the systems of users that have access to the same samba share.
Proposed upstream patch:
This issue did not affect the Linux kernel as shipped with Red Hat Enterprise
Linux 4 and 5 as they did not backport the commit
a6ce4932fbdbcd8f8e8c6df76812014351c32892 that introduced this issue. This issue did not affect the Linux kernel as shipped with Red Hat Enterprise MRG 2. This has been addressed in Red Hat Enterprise Linux 6 via https://rhn.redhat.com/errata/RHSA-2012-0481.html.
Added CVE-2012-1090 as per http://www.openwall.com/lists/oss-security/2012/02/28/4
kernel-220.127.116.11-1.fc15 has been pushed to the Fedora 15 stable repository. If problems still persist, please make note of it in this bug report.
This issue has been addressed in following products:
Red Hat Enterprise Linux 6
Via RHSA-2012:0481 https://rhn.redhat.com/errata/RHSA-2012-0481.html