Bug 156145 - kernel may oops if more than 4k worth of string data returned in /proc/devices
kernel may oops if more than 4k worth of string data returned in /proc/devices
Status: CLOSED ERRATA
Product: Red Hat Enterprise Linux 4
Classification: Red Hat
Component: kernel (Show other bugs)
4.0
All Linux
medium Severity medium
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Assigned To: Neil Horman
Brian Brock
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Depends On:
Blocks: 181409
  Show dependency treegraph
 
Reported: 2005-04-27 16:49 EDT by Chris Williams
Modified: 2007-11-30 17:07 EST (History)
3 users (show)

See Also:
Fixed In Version: RHSA-2006-0575
Doc Type: Bug Fix
Doc Text:
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Clone Of:
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Last Closed: 2006-08-10 17:04:27 EDT
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RHEL 7.3 requirements from Atomic Host:
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Attachments (Terms of Use)
RHEL4 patch to fix /proc/devices buffer overrun (2.50 KB, patch)
2005-04-29 14:58 EDT, Neil Horman
no flags Details | Diff
backport of latest upstream version of /proc/devices patch (5.87 KB, patch)
2006-04-24 13:31 EDT, Neil Horman
no flags Details | Diff
patch to prevent /proc/devices buffer overflow (5.65 KB, patch)
2006-05-02 16:31 EDT, Neil Horman
no flags Details | Diff

  None (edit)
Description Chris Williams 2005-04-27 16:49:33 EDT
+++ 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 14:58:29 EDT
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 15:41:39 EDT
This shouldn't block on the 2.1 version of this bug.
Comment 16 Neil Horman 2006-04-24 13:31:13 EDT
Created attachment 128155 [details]
backport of latest upstream version of /proc/devices patch
Comment 17 Jason Baron 2006-04-25 22:03:52 EDT
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 13:41:58 EDT
patch reverted due to kabi issues.
Comment 20 Neil Horman 2006-05-02 16:31:53 EDT
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 13:11:24 EDT
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 17:04:28 EDT
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

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