On 04/22/18 08:35, Keith Mendoza wrote:
Bart,
I was actually working on this yesterday. This is what I know so far after a
few hours of digging into this: It appears that there's an issue with getting
to the memory address that EVP_sha512() returns when it's called in
sc_get_openssl_hashfn(). Why this is so, I don't know. Below are details of
what I've figured out so far:
On my environment, I'm using OpenSSL 1.0.2o installed using mac ports.
EVP_sha512() simply returns the address of a static const struct env_md_st
instance once you expand the EVP_MD typedef (see the source here:
https://github.com/openssl/openssl/blob/3ce7bc40a3c48da1c96c2d04c10045bd797c6aa3/crypto/evp/m_sha1.c#L216).
When I was stepping through using the lldb debugger, when I inspect the value
of hashfn after the call to EVP_sha512() it actually reports an error that the
address is inaccessible. That one's got me stumped. In line 192, the call
EVP_DigestInit() happens and the address returned by EVP_sha512() is passed as
the 2nd parameter to that function. Kaboom for obvious reasons.
I'm no expert on the rules of accessing memory space from dynamic libraries.
Hopefully, someone else can chime in. My next step is to write a small test
program to isolate the digest initialization code to see if I can replicate the
issue outside of Net-SNMP.
Hello Keith,
Can you have a look at the openssl/evp.h header file? The following
warning appears in the OS/X build output, which is suspicious:
scapi.c:88:12: warning: implicit declaration of function 'EVP_sha224' is
invalid in C99 [-Wimplicit-function-declaration]
return EVP_sha224();
^
Thanks,
Bart.
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