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Bug 217621

Summary: kernel may oops if more than 4k worth of string data returned in /proc/devices
Product: Red Hat Enterprise Linux 2.1 Reporter: Don Howard <dhoward>
Component: kernelAssignee: Don Howard <dhoward>
Status: CLOSED ERRATA QA Contact: Brian Brock <bbrock>
Severity: medium Docs Contact:
Priority: medium    
Version: 2.1CC: tao
Target Milestone: ---   
Target Release: ---   
Hardware: ia64   
OS: Linux   
Whiteboard:
Fixed In Version: RHSA-2007-0012 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2007-01-17 10:51:44 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:

Description Don Howard 2006-11-28 23:38:46 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 Mike Gahagan 2006-12-19 22:55:28 UTC 
I was unable to reproduce the problem with the test module from bz 156029,
however I have verified that the fix is being applied in the 2.4.18-e.64 kernel.
Comment 5 Red Hat Bugzilla 2007-01-17 10:51:44 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-2007-0012.html