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Bug 156142

Summary: kernel may oops if more than 4k worth of string data returned in /proc/devices
Product: Red Hat Enterprise Linux 3 Reporter: Chris Williams <cww>
Component: kernelAssignee: Neil Horman <nhorman>
Status: CLOSED ERRATA QA Contact: Brian Brock <bbrock>
Severity: medium Docs Contact:
Priority: medium    
Version: 3.0CC: bmaly, jburke, mwesley, peterm, petrides, tao
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: RHSA-2005-663 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2005-09-28 15:00:19 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:
Bug Depends On:    
Bug Blocks: 156320    
Attachments:
Description Flags
rhkl patch accepted to fix this problem
none
rhkl patch accepted to fix this problem none

Description Chris Williams 2005-04-27 20:44:43 UTC 
+++ This bug was initially created as a clone of Bug #156029 +++

Description of problem:
the read routine for /proc/devices is missing a length check routine. 
Consequently, if the number of block and char devices in a system totals more
than 4096 bytes of string data between their names and major/minor numbers, the
read routine will sprintf the data off the end of the page and oops the kernel.
other proc files that are part of proc_misc.c protect against this with a length
check that truncates the file if it goes over a page, but this check is missing
from get_device_list and get_blkdev_list.

Version-Release number of selected component (if applicable):
all

How reproducible:
always

Steps to Reproduce:
1. register sufficient char/block devices in a system to create > 4096 bytes of
string data for /proc/devices
2. cat /proc/devices
3.
  
Actual results:
system will oops on a page fault

Expected results:
system should truncate file to 4096 bytes.

Additional info:
Comment 3 Ernie Petrides 2005-05-05 00:40:36 UTC 
A fix for this problem has just been committed to the RHEL3 U6
patch pool this evening (in kernel version 2.4.21-32.3.EL).
Comment 6 Neil Horman 2005-05-17 00:48:02 UTC 
I wrote a module to register dummy character devices and block devices to fill
up the page in /proc/devices.  Pretty straightforward.  Do you want it?
Comment 8 Neil Horman 2005-05-17 11:11:16 UTC 
Created attachment 114458 [details]
rhkl patch accepted to fix this problem

Sorry, arjan, I thought it was already added here.  This is what was accepted
on rhkl. Its pretty unobtrusive.
Comment 9 Neil Horman 2005-05-17 11:11:40 UTC 
Created attachment 114459 [details]
rhkl patch accepted to fix this problem

Sorry, arjan, I thought it was already added here.  This is what was accepted
on rhkl. Its pretty unobtrusive.  I'll dig out my test code (need to remember
where I put it), and post it here shortly
Comment 18 Red Hat Bugzilla 2005-09-28 15:00:20 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-2005-663.html