Bug 682954 (CVE-2011-1093)

Summary:	CVE-2011-1093 kernel: dccp: fix oops on Reset after close
Product:	[Other] Security Response	Reporter:	Eugene Teo (Security Response) <eteo>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	arozansk, bhu, bressers, dhoward, jkacur, kernel-mgr, kmcmartin, kzhang, lgoncalv, lwang, pmatouse, rkhan, rt-maint, tcallawa, tkubota, vkrizan, williams
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2015-07-29 14:08:27 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:	682955, 682956, 682957, 682958, 682959, 745792
Bug Blocks:

Description Eugene Teo (Security Response) 2011-03-08 06:02:26 UTC

This fixes a bug in the order of dccp_rcv_state_process() that still permitted
reception even after closing the socket. A Reset after close thus causes a NULL
pointer dereference by not preventing operations on an already torn-down socket.

 dccp_v4_do_rcv()
|
| state other than OPEN
v
 dccp_rcv_state_process()
|
| DCCP_PKT_RESET
v
 dccp_rcv_reset()
|
v
 dccp_time_wait()

 WARNING: at net/ipv4/inet_timewait_sock.c:141 __inet_twsk_hashdance+0x48/0x128()
 Modules linked in: arc4 ecb carl9170 rt2870sta(C) mac80211 r8712u(C) crc_ccitt ah
 [<c0038850>] (unwind_backtrace+0x0/0xec) from [<c0055364>] (warn_slowpath_common)
 [<c0055364>] (warn_slowpath_common+0x4c/0x64) from [<c0055398>] (warn_slowpath_n)
 [<c0055398>] (warn_slowpath_null+0x1c/0x24) from [<c02b72d0>] (__inet_twsk_hashd)
 [<c02b72d0>] (__inet_twsk_hashdance+0x48/0x128) from [<c031caa0>] (dccp_time_wai)
 [<c031caa0>] (dccp_time_wait+0x40/0xc8) from [<c031c15c>] (dccp_rcv_state_proces)
 [<c031c15c>] (dccp_rcv_state_process+0x120/0x538) from [<c032609c>] (dccp_v4_do_)
 [<c032609c>] (dccp_v4_do_rcv+0x11c/0x14c) from [<c0286594>] (release_sock+0xac/0)
 [<c0286594>] (release_sock+0xac/0x110) from [<c031fd34>] (dccp_close+0x28c/0x380)
 [<c031fd34>] (dccp_close+0x28c/0x380) from [<c02d9a78>] (inet_release+0x64/0x70)

The fix is by testing the socket state first. Receiving a packet in Closed state now also produces the required "No connection" Reset reply of RFC 4340, 8.3.1.

Upstream commit:
http://git.kernel.org/linus/720dc34bbbe9493c7bd48b2243058b4e447a929d

Comment 7 Eugene Teo (Security Response) 2011-03-15 01:24:38 UTC

Statement:

This issue did not affect the version of Linux kernel as shipped with Red Hat Enterprise Linux 4 as it did not include support for the DCCP protocol. Future updates in Red Hat Enterprise Linux 5, 6 and Red Hat Enterprise MRG may address this flaw.

Comment 8 Eugene Teo (Security Response) 2011-03-15 03:16:57 UTC

Mitigation:

For users that do not run applications that use DCCP, you can prevent the dccp
module from being loaded by adding the following entry to the end of the
/etc/modprobe.d/blacklist file:

blacklist dccp

This way, the dccp module cannot be loaded accidentally, which may occur if an
application that requires DCCP is started. A reboot is not necessary for this
change to take effect but do make sure the module is not loaded in the first
place. You can verify that by running:

lsmod | grep dccp

You may also consider removing the CAP_SYS_MODULE capability from the current
global capability set to prevent kernel modules from being loaded or unloaded.
The CAP_SYS_MODULE has a capability number of 16 (see linux/capability.h). The
default value has all the bits set. To remove this capability, you have to
clear the 16th bit of the default 32-bit value, e.g. 0xffffff ^ (1 << 16):

echo 0xFFFEFFFF > /proc/sys/kernel/cap-bound

Comment 9 Liang Zheng 2011-04-20 04:39:01 UTC

Fail to modprobe dccp
See:https://bugzilla.redhat.com/show_bug.cgi?id=698062
and 
dccp: fix bug in cache allocation
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=8ed030dd0aa400d18c63861c2c6deb7c38f4edde

Comment 10 errata-xmlrpc 2011-05-10 17:19:54 UTC

This issue has been addressed in following products:

  MRG for RHEL-5

Via RHSA-2011:0500 https://rhn.redhat.com/errata/RHSA-2011-0500.html

Comment 11 errata-xmlrpc 2011-05-10 18:10:48 UTC

This issue has been addressed in following products:

  Red Hat Enterprise Linux 6

Via RHSA-2011:0498 https://rhn.redhat.com/errata/RHSA-2011-0498.html

Comment 12 errata-xmlrpc 2011-05-31 14:05:49 UTC

This issue has been addressed in following products:

  Red Hat Enterprise Linux 5

Via RHSA-2011:0833 https://rhn.redhat.com/errata/RHSA-2011-0833.html