Bug 658230

Summary: dirmngr crashes when OCSP reply contains a byKey responderID
Product: [Fedora] Fedora Reporter: Tomáš Trnka <tomastrnka>
Component: dirmngrAssignee: Rex Dieter <rdieter>
Status: CLOSED WONTFIX QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: low    
Version: 14CC: rdieter, tmraz
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Hardware: x86_64   
OS: Linux   
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2012-08-16 22:13:34 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Flags
Full OCSP response (dissected using Wireshark)
none
Simple fix/workaround none

Description Tomáš Trnka 2010-11-29 18:10:11 UTC 
Created attachment 463543 [details]
Full OCSP response (dissected using Wireshark)

Description of problem:
After enabling OCSP validity checks, dirmngr keeps crashing as soon as he hits a certificate issued by Quo Vadis CA. My investigation revealed that the OCSP responder at http://ocsp.quovadisglobal.com returns responses without a responder name (the responderID field contains only a key ID):

Online Certificate Status Protocol
    responseStatus: successful (0)
    responseBytes
        ResponseType Id: 1.3.6.1.5.5.7.48.1.1 (id-pkix-ocsp-basic)
        BasicOCSPResponse
            tbsResponseData
                responderID: byKey (2)
                    byKey: bef04a7291f5dd978877cfb9bf3597dd90041011

When this is parsed by libksba's parse_response_data, the responder_id.name field remains NULL. The ksba_ocsp_get_responder_id() call in check_signature() (dirmngr's ocsp.c) then copies this NULL into the "name" argument. The subsequent call to find_cert_bysubject() passes this "name" (subject_dn) to strcmp, leading to a null pointer dereference crash.

Version-Release number of selected component (if applicable):
dirmngr-1.1.0-1.fc14.x86_64
libksba-1.0.8-1.fc14.x86_64

How reproducible:
100%

Steps to Reproduce:
1. LANG=C gpgsm --list-keys --with-validation 0x2D938845
2. Segfault in dirmngr
  
Actual results:
#0  0x00000034f2a8133a in __strcmp_sse2 () from /lib64/libc.so.6
#1  0x00000000004129f7 in find_cert_bysubject (ctrl=0x850020, subject_dn=0x0, 
    keyid=0x8558d0 "(20:\276\360Jr\221\365ݗ\210wϹ\277\065\227ݐ\004\020\021)") at certcache.c:1149
#2  0x000000000041acc5 in check_signature (ctrl=0x850020, cert=0x857590, cert_fpr=<value optimized out>, 
    force_default_responder=<value optimized out>) at ocsp.c:481
#3  ocsp_isvalid (ctrl=0x850020, cert=0x857590, cert_fpr=<value optimized out>, force_default_responder=<value optimized out>) at ocsp.c:663
#4  0x000000000040a8a8 in cmd_isvalid (ctx=0x8540b0, line=<value optimized out>) at server.c:540
#5  0x00000034f2e06c87 in dispatch_command (ctx=0x8540b0, 
    line=0x8541f8 "atement.0\"\006\b+\006\001\005\005\a\002\001\026\026http://www.quovadis.bm0\016\006\003U\035\017\001\001\377\004\004\003\002\001\006\060\201\256\006\003U\035#\004\201\246\060\201\243\200\024\213Km\355\323)\271\006\031\354\071\071\251\360\227\204j\313\357ߡ\201\204\244\201\201\060\177\061\v0\t\006\003U\004\006\023\002BM1\031\060\027\006\003U\004%0A\023\020QuoVadis Limited1%250#\006\003U\004\v\023\034Root Certification Authority1.0,\006\003U\004\003\023%25"..., linelen=<value optimized out>) at assuan-handler.c:561
#6  0x00000034f2e07af9 in process_request (ctx=0x8540b0) at assuan-handler.c:748
#7  assuan_process (ctx=0x8540b0) at assuan-handler.c:771
#8  0x000000000040b21f in start_command_handler (fd=<value optimized out>) at server.c:1445
#9  0x00000000004087d5 in main (argc=0, argv=0x7fffffffdfd8) at dirmngr.c:967
Comment 1 Tomáš Trnka 2010-11-29 18:12:28 UTC 
Created attachment 463544 [details]
Simple fix/workaround

This patch prevents the crash, but the validation still fails with:

gpgsm: unable to find the certificate used by the dirmngr: Unknown system error
  [checking the CRL failed: Invalid CRL]
  [validation model used: shell]
  [certificate is bad: Invalid CRL]
Comment 2 Tomas Mraz 2010-12-01 13:20:38 UTC 
I've reported the issue upstream. I suppose some substantial code changes will be needed to properly match such OCSP responses.

In the meanwhile I fix the crasher by your patch. Thanks.
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