|Summary:||CVE-2007-0005 Buffer Overflow in Omnikey CardMan 4040 cmx driver|
|Product:||Red Hat Enterprise Linux 5||Reporter:||Linda Wang <lwang>|
|Component:||kernel||Assignee:||Don Howard <dhoward>|
|Status:||CLOSED ERRATA||QA Contact:||Brian Brock <bbrock>|
|Fixed In Version:||RHSA-2007-0099||Doc Type:||Bug Fix|
|Doc Text:||Story Points:||---|
|Last Closed:||2007-03-14 15:05:01 UTC||Type:||---|
|oVirt Team:||---||RHEL 7.3 requirements from Atomic Host:|
|Cloudforms Team:||---||Target Upstream Version:|
Comment 7 Marcel Holtmann 2007-03-02 15:56:48 UTC
From Daniel Roethlisberger wrote While using the Linux drivers for the CM4040 as a reference for writing a cmx FreeBSD driver I found two buffer overflows in the Linux drivers, one in the write() and one in the read() handler. When calling write() with a buffer larger than 512 bytes, the driver's write buffer overflows, allowing to overwrite the EIP and execute arbitrary code with kernel privileges. In read(), we have a similar problem, but coming from the device. A malicous or buggy device sending more than 512 bytes can overflow of the driver's read buffer, with the same effects as above. The write() vulnerability can only be exploited by a user with direct or indirect write access to the cmx device special file. Normally, this is limited to root, so this is not an issue. However, it might be possible for unprivileged users to cause large writes indirectly via userland daemons such as those provided by pcsc-lite or openct. Since "normal" APDU payloads are smaller than 512 bytes, this may not be an issue, but I haven't looked into that. Furthermore, a system can be set up to allow access to the device for a special user or group, in order to increase security by running the userland drivers without root privileges. In such a setup, users with access to the device can elevate privileges or cause DoS. The problem code in cm4040_cs.c:cm4040_write() is on line 358 (current version in Linus' git tree), when calling copy_from_user() with user supplied bytes_to_write, which can be larger than 512 bytes. Because it does not seem to make sense to write partial messages to this card reader, I think it is best to return an appropriate error on write()'s larger than the write buffer. This is what I do in the FreeBSD driver. The problem code in cm4040_cs.c:cm4040_read() is around line 271 where bytes_to_read is read from the card reader, and subsequently, min(count, bytes_to_read + 5) bytes are read from the reader. min(count, bytes_to_read + 5) can however be larger than the read buffer, which would cause an overflow.
Comment 9 Marcel Holtmann 2007-03-06 17:43:07 UTC
The embargo ended on 6th of March.
Comment 12 Red Hat Bugzilla 2007-03-14 15:05:01 UTC
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on the solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2007-0099.html