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Bug 197670

Summary: CVE-2006-2935 Possible buffer overflow in DVD handling
Product: Red Hat Enterprise Linux 4 Reporter: Marcel Holtmann <holtmann>
Component: kernelAssignee: Chip Coldwell <coldwell>
Status: CLOSED ERRATA QA Contact: Brian Brock <bbrock>
Severity: medium Docs Contact:
Priority: medium    
Version: 4.0CC: jbaron, security-response-team
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard: impact=moderate,source=kernelbugzilla,reported=20060705,public=20060627
Fixed In Version: RHSA-2006-0617 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2006-08-22 18:50:35 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Attachments:
Description Flags
Proposed patch from Jens Axboe none

Description Marcel Holtmann 2006-07-05 13:23:20 UTC 
Reported by Marcus Meissner to the Kernel Bugzilla:

http://bugzilla.kernel.org/show_bug.cgi?id=2966

The dvd_read_bca() function in drivers/cdrom/cdrom.c shows a potential buffer
overflow. 
 
The variable buf[4+188] is allocated on the stack, however cgc.cmd[9] and
cgc.buflen are set to 255:

cgc.cmd[9] = cgc.buflen = 0xff;
 
This can be exploited by a custom made USB Storage device and used for local
privilege escalation (aka plug-in this USB device to get root).

This function has been introduced in 2.2.16 (back in 2000) and as of today it
hasn't changed. Jens Axboe confirmed that this is a typo and it should read:

cgc.cmd[9] = cgc.buflen & 0xff;

It is to mask high bits of the length. It doesn't use the high 8 bits for
transfer length, since we are always < 256 for this case.
Comment 1 Marcel Holtmann 2006-07-05 13:25:45 UTC 
Created attachment 131920 [details]
Proposed patch from Jens Axboe
Comment 3 Jason Baron 2006-08-07 18:49:47 UTC 
committed in stream E5 build 42.0.1. A test kernel with this patch is available
from http://people.redhat.com/~jbaron/rhel4/
Comment 6 Red Hat Bugzilla 2006-08-22 18:50:37 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-2006-0617.html
Comment 8 Jason Baron 2006-08-30 17:48:26 UTC 
committed in stream U5 build 42.4. A test kernel with this patch is available
from http://people.redhat.com/~jbaron/rhel4/