Bug 697822 (CVE-2011-1593)

Summary: CVE-2011-1593 kernel: proc: signedness issue in next_pidmap()
Product: [Other] Security Response Reporter: Petr Matousek <pmatouse>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: arozansk, bhu, dhoward, jkacur, kernel-mgr, kmcmartin, lgoncalv, lwang, rkhan, rt-maint, sforsber, tcallawa, vgoyal, williams
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2015-07-29 12:39:47 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 697824, 697825, 697826, 697827, 697828, 697838    
Bug Blocks:    

Description Petr Matousek 2011-04-19 11:42:20 UTC
A signedness issue has been found in next_pidmap() function when the "last"
parameter is negative as next_pidmap() just quietly accepted whatever
"last" pid that was passed in, which is not all that safe when one of the
users is /proc.

Setting f_pos to negative value when accessing /proc via readdir()/getdents()
resulted in sign extension of this value when map pointer was being

This later lead to #GP becasue the final pointer was not cannonical (x86_64).

map = &pid_ns->pidmap[(last + 1)/BITS_PER_PAGE];
 ffffffff810ac3b4:       48 63 f6                movslq %esi,%rsi      <- sign extension (f_pos+-)
 ffffffff810ac3b7:       81 e2 ff 7f 00 00       and    $0x7fff,%edx 
 ffffffff810ac3bd:       48 c1 ee 0f             shr    $0xf,%rsi
 ffffffff810ac3c1:       48 c1 e6 04             shl    $0x4,%rsi
 ffffffff810ac3c5:       48 8d 5c 37 08          lea    0x8(%rdi,%rsi,1),%rbx 
if (unlikely(!map->page)) 
 ffffffff810ac3cc:       48 8b 7b 08             mov    0x8(%rbx),%rdi <- #GP

Only x86_64 architecture seems to be vulnerable to this particular issue
(tested ppc64, s390x, ia64).


Upstream commit:


Red Hat would like to thank Robert Swiecki for reporting this issue.

Comment 5 Petr Matousek 2011-05-02 09:58:00 UTC

This issue affects the versions of Linux kernel as shipped with Red Hat
Enterprise Linux 4, 5, 6, and Red Hat Enterprise MRG. This has been addressed in Red Hat Enterprise Linux 5, 6 and Red Hat Enterprise MRG via https://rhn.redhat.com/errata/RHSA-2011-0927.html, https://rhn.redhat.com/errata/RHSA-2011-1189.html, and https://rhn.redhat.com/errata/RHSA-2011-1253.html. Red Hat Enterprise Linux 4 is now in Production 3 of the maintenance life-cycle, https://access.redhat.com/support/policy/updates/errata/, therefore the fix for this issue is not currently planned to be included in the future updates.

Comment 6 errata-xmlrpc 2011-07-15 06:09:03 UTC
This issue has been addressed in following products:

  Red Hat Enterprise Linux 5

Via RHSA-2011:0927 https://rhn.redhat.com/errata/RHSA-2011-0927.html

Comment 7 errata-xmlrpc 2011-08-23 14:42:20 UTC
This issue has been addressed in following products:

  Red Hat Enterprise Linux 6

Via RHSA-2011:1189 https://rhn.redhat.com/errata/RHSA-2011-1189.html

Comment 8 errata-xmlrpc 2011-09-12 19:45:15 UTC
This issue has been addressed in following products:

  MRG for RHEL-6 v.2

Via RHSA-2011:1253 https://rhn.redhat.com/errata/RHSA-2011-1253.html