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Bug 156145

Summary: kernel may oops if more than 4k worth of string data returned in /proc/devices
Product: Red Hat Enterprise Linux 4 Reporter: Chris Williams <cww>
Component: kernelAssignee: Neil Horman <nhorman>
Status: CLOSED ERRATA QA Contact: Brian Brock <bbrock>
Severity: medium Docs Contact:
Priority: medium    
Version: 4.0CC: davej, jbaron, tao
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: RHSA-2006-0575 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2006-08-10 21:04:27 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: 181409    
Attachments:
Description Flags
RHEL4 patch to fix /proc/devices buffer overrun
none
backport of latest upstream version of /proc/devices patch
none
patch to prevent /proc/devices buffer overflow none

Description Chris Williams 2005-04-27 20:49:33 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 Neil Horman 2005-04-29 18:58:29 UTC 
Created attachment 113865 [details]
RHEL4 patch to fix /proc/devices buffer overrun

This is the patch posted to RHKL
Comment 4 Neil Horman 2005-06-20 19:41:39 UTC 
This shouldn't block on the 2.1 version of this bug.
Comment 16 Neil Horman 2006-04-24 17:31:13 UTC 
Created attachment 128155 [details]
backport of latest upstream version of /proc/devices patch
Comment 17 Jason Baron 2006-04-26 02:03:52 UTC 
committed in stream U4 build 34.24. A test kernel with this patch is available
from http://people.redhat.com/~jbaron/rhel4/
Comment 18 Jason Baron 2006-05-01 17:41:58 UTC 
patch reverted due to kabi issues.
Comment 20 Neil Horman 2006-05-02 20:31:53 UTC 
Created attachment 128516 [details]
patch to prevent /proc/devices buffer overflow

same patch as before, but added __GENKSYMS__ macro around seq_file.h include to
prevent abi breakage.  posted to rhkl
Comment 21 Jason Baron 2006-05-04 17:11:24 UTC 
committed in stream U4 build 35.1. A test kernel with this patch is available
from http://people.redhat.com/~jbaron/rhel4/
Comment 25 Red Hat Bugzilla 2006-08-10 21:04:28 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-2006-0575.html