Bug 795913 (CVE-2012-0875)

Summary: CVE-2012-0875 systemtap: kernel panic when processing malformed DWARF unwind data
Product: [Other] Security Response Reporter: Vincent Danen <vdanen>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: fche, mjw, scox, security-response-team
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard: impact=moderate,public=20120220,reported=20120221,source=internet,cvss2=5.2/AV:L/AC:L/Au:S/C:P/I:N/A:C,rhel-5/systemtap=affected,rhel-6/systemtap=affected,fedora-all/systemtap=affected
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2013-02-28 11:21:22 EST Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---
Bug Depends On: 796325, 796326, 796327, 796328, 796329    
Bug Blocks: 795947    

Description Vincent Danen 2012-02-21 14:36:26 EST
A flaw was discovered [1] in how systemtap handled DWARF expressions when unwinding the stack.  This could result in an invalid pointer read, leading to reading kernel memory, or a kernel panic (and if the kernel reboot on panic flag was set (panic_on_oops), it would cause the system to reboot).

In order to trigger this flaw, an admin would have to enable unprivileged mode (giving users membership in the 'stapusr' group and configuring the local machine with 'signer,all-users' stap-server trust). If an admin has enabled unprivileged mode, a user with such access could use this to crash the local machine.

A workaround is to disable unprivileged mode.

This will be corrected in a forthcoming upstream release of systemtap, and is currently fixed in git [2].  It is believed that this flaw was introduced via git commit 16d59279f [3], so would affect systemtap >= 1.4.

[1] http://sourceware.org/bugzilla/show_bug.cgi?id=13714
[2] http://sourceware.org/git/?p=systemtap.git;a=commit;h=64b0cff3b
[3] http://sourceware.org/git/?p=systemtap.git;a=commit;h=16d59279f
Comment 2 Vincent Danen 2012-02-22 12:18:08 EST
Created systemtap tracking bugs for this issue

Affects: fedora-all [bug 796329]
Comment 5 errata-xmlrpc 2012-03-08 16:13:58 EST
This issue has been addressed in following products:

  Red Hat Enterprise Linux 5
  Red Hat Enterprise Linux 6

Via RHSA-2012:0376 https://rhn.redhat.com/errata/RHSA-2012-0376.html