Bug 741892

Same issue as that appearing in the EPEL bug report, the following patch needs to be backported against m2cryto to fix


http://git.fedorahosted.org/git/?p=pulp.git;a=blob;f=rpm/m2crypto/m2crypto-0.21.1-x509_crl.patch


+++ This bug was initially created as a clone of Bug #707676 +++

Description of problem:

m2crypto loading x509 cert causes Segmentation fault for python26 but not for python form RHEL.

Version-Release number of selected component (if applicable):

I am comparing these versions.

python26-m2crypto-0.21.1-3.el5
m2crypto-0.16-7.el5

How reproducible:

Every time

Steps to Reproduce:

0. Install both version's of m2crypto for RHEL5.

# yum install python26-m2crypto m2crypto

1. Make python script

#cat fred.py 
from M2Crypto import SMIME, X509, BIO
st = X509.X509_Store()
st.load_info('/etc/grid-security/certificates/bffbd7d0.0')
print st

2. Run with "python"

# python fred.py 
<M2Crypto.X509.X509_Store instance at 0xca3878>

3. Run with python2.6

# python2.6  fred.py 
Segmentation fault

For me a 0.18 or higher version of M2Crypto in RHEL would also be fine I don't need python26, unfortunately the RHEL 5 version is m2crypto-0.16-6.el5.6 which does not support verifying X509 SMIME signed messages, here is some of my code, that I cant get to run on RHEL version of m2crypto.

def validate_text(self,text_to_verify):
    buf = BIO.MemoryBuffer(text_to_verify)
    sk = X509.X509_Stack()
    p7, data = SMIME.smime_load_pkcs7_bio(buf)
    try:
        supplied_stack =  p7.get0_signers(sk)
    except AttributeError, e:
        if str(e) == "PKCS7 instance has no attribute 'get0_signers'":
             self.logger.error('m2crypto version 0.18 is the minimum supported, please upgrade.')
        raise e

I mark this as urgent, as although only in EPEL their is no way to make your code verify X509 signed SMIME messages in python without using the openssl library via the command line. (I know it all works fine in RHEL6 and its a known limitation with m2crypto 0.16 and 0.17, just google "get0_signers") 

Thank you for taking the time to look into this bug, I hope you get time to add the issue to your test suites.

Regards

Owen

--- Additional comment from mitr on 2011-05-25 15:20:25 EDT ---

Relevant part of disassembly:
> 0x00002aaaaf27b7f2 <_wrap_x509_store_load_locations+130>:	mov    0x20(%rsp),%rbx
> 0x00002aaaaf27b7f7 <_wrap_x509_store_load_locations+135>:	callq  0x2aaaaf279970 <SWIG_AsCharPtrAndSize>

* arg1 == argp1 is loaded into %rbx at ...b7f2.
* ...b7f7 calls SWIG_AsCharPtrAndSize
* SWIG_AsCharPtrAndSize stores %rbx on the stack, and eventually calls
> char *cstr; int len;
> PyString_AsStringAndSize(obj, &cstr, &len);
* However, the second patameter of PyString_AsStringAndSize is actually a pointer to Py_ssize_t (64bit instead of 32-bit)
* Thus, the %rbx value saved on stack is overwritten by zeroes
* ... and eventually X509_STORE_load_locations is called with the first parameter equal to NULL

So, this all seems to be caused by the fact that the swig in RHEL does not support Python 2.6.

--- Additional comment from mitr on 2011-05-25 15:25:29 EDT ---

As for the missing get0_signers in m2crypto-0.16-7.el5, if you are a Red Hat customer with an active subscription, please report this via the Red Hat Customer Portal at http://access.redhat.com/ to allow correct prioritization of this issue.

--- Additional comment from gholms on 2011-05-25 18:25:07 EDT ---

This is a swig issue that happens when building against Python >= 2.5 on 64-bit systems.  Upstream fixed this bug in its svn repo ages ago with a very small change to the code, so bug 707778 attempts to get that fix backported to RHEL 5's swig package.  If that happens then this bug can be fixed with a recompile.  Otherwise I can look into monkey-patching _m2crypto_wrapper.c, though that is less than ideal.

For posterity's sake, here is a minimal reproducer:
> yum install python26-m2crypto
> python2.6 << EOF
> from M2Crypto import X509
> store = X509.X509Store()
> store.load_info('/etc/pki/tls/certs/ca-bundle.crt')
> EOF

--- Additional comment from owen.synge on 2011-05-26 06:40:27 EDT ---

Dear all,

Thankyou for the work on this area.

Miloslav Trma\u010d, Sorry I am not a redhat customer, I am a Scientfic Linux user.

Regards

Owen

--- Additional comment from dmalcolm on 2011-06-07 16:31:08 EDT ---

Possible alternate approach (though v. ugly): hack up the build of python26-m2crypto to apply the patch seen in bug 707778 to the code that SWIG generates (IIRC, the files that that patch touches are templates used by the code generator.  I could be misremembering).