Red Hat Bugzilla – Full Text Bug Listing
|Summary:||Crash in __pmDecodeCreds decoding crafted PDUs|
|Product:||[Fedora] Fedora||Reporter:||Florian Weimer <fweimer>|
|Component:||pcp||Assignee:||Nathan Scott <nathans>|
|Status:||CLOSED ERRATA||QA Contact:||Fedora Extras Quality Assurance <extras-qa>|
|Version:||16||CC:||fche, kenj, mgoodwin, nathans, security-response-team, vdanen|
|Fixed In Version:||pcp-3.6.5||Doc Type:||Bug Fix|
|Doc Text:||Story Points:||---|
|Last Closed:||2012-08-19 23:52:18 EDT||Type:||Bug|
|oVirt Team:||---||RHEL 7.3 requirements from Atomic Host:|
|Bug Depends On:|
|Bug Blocks:||840765, 841698|
Description Florian Weimer 2012-07-17 05:59:48 EDT
pmcd (and probably others) in pcp-3.6.3 crash when decoding crafted PDUs where the numcreds field exceeds the number of elements actually contained in the PDU. On 32-bit architectures, the size passed to malloc can be too small, leading to a heap-based buffer overflow. On 64-bit architectures, the multiplication is performed with 64 bits, so no overflow occurs, and the crash happens because __pmDecodeCreds reads beyond the end of an allocated buffer. pmcd runs with root privileges and starts automatically when the pcp package is installed. It listens on 0.0.0.0 and does not require authentication.
Comment 8 Mark Goodwin 2012-07-17 20:30:25 EDT
Created attachment 598767 [details] preliminary patch to __pmDecodeCreds to fix this Attached preliminary patch from Nathan Scott (upstream). Has been tested against the reproducer script.
Comment 9 Florian Weimer 2012-07-18 02:54:43 EDT
(In reply to comment #8) > Created attachment 598767 [details] > preliminary patch to __pmDecodeCreds to fix this > > > Attached preliminary patch from Nathan Scott (upstream). Has been tested > against the reproducer script. This calculation can overflow: need = sizeof(creds_t) + ((numcred-1) * sizeof(__pmCred)); There should be a check *before* the calculation that this cannot happen, something like numcred < (INT_MAX - sizeof(creds_t))/sizeof(__pmCred).
Comment 10 Nathan Scott 2012-07-19 06:18:37 EDT
Created attachment 599108 [details] Updated patch to address pcp credentials pdu buffer overflow exploit Incorporates an additional check to guard against malloc size overflow. Uses a tighter restriction than the MAXINT-based suggestion, based on current uses and likely future uses of this PDU.
Comment 11 Mark Goodwin 2012-07-19 06:23:23 EDT
Ressign to Nathan since he is following thru and this seems to be the way to go for these bugs.
Comment 12 Nathan Scott 2012-07-19 06:25:03 EDT
I have a pcpqa test (513) which uses Florian's initial test case to exercise this change. I'll hang onto it privately until we get a/ confirmation on permission to make use of this, and b/ public knowledge of the issue. thanks!
Comment 13 Florian Weimer 2012-07-19 07:33:00 EDT
(In reply to comment #10) > Created attachment 599108 [details] > Updated patch to address pcp credentials pdu buffer overflow exploit > > Incorporates an additional check to guard against malloc size overflow. > Uses a tighter restriction than the MAXINT-based suggestion, based on > current uses and likely future uses of this PDU. This looks good, thanks.
Comment 14 Huzaifa S. Sidhpurwala 2012-08-15 23:41:32 EDT
Upstream patch: http://oss.sgi.com/cgi-bin/gitweb.cgi?p=pcp/pcp.git;a=commit;h=cced6012b4b93bfb640a9678589ced5416743910 This issue has been addressed in pcp-3.6.5
Comment 15 Huzaifa S. Sidhpurwala 2012-08-19 23:52:18 EDT
This issue was addressed in Fedora and EPEL via the following security updates: Fedora-16: https://admin.fedoraproject.org/updates/pcp-3.6.5-1.fc16 Fedora-17: https://admin.fedoraproject.org/updates/pcp-3.6.5-1.fc17 Rawhide: https://admin.fedoraproject.org/updates/pcp-3.6.5-1.fc18 EPEL-5: https://admin.fedoraproject.org/updates/pcp-3.6.5-1.el5 EPEL-6: https://admin.fedoraproject.org/updates/pcp-3.6.5-1.el6