Re: Segfaults on FreeBSD

On Tue, May 4, 2021 at 2:08 PM Rogier <[email protected]> wrote:
>
> I keep getting segfaults within cryptopp on freebsd for at least PBKDF DeriveKey(). I used the sample code from the wiki:
> https://www.cryptopp.com/wiki/PKCS12_PBKDF
>
> I used the cryptopp-lib that is available through the binary ports collection (pkg). The reported version is 8.5.0
>
> Any ideas on how I can fix this or at least where to look?
>
> Below all the technical info about versions and traces for a first triage.

Ugh... I can duplicate this, too using FreeBSD's version of the library.

It looks like the problem is at frame 3:

#3  0x0000000000207739 in CryptoPP::HashTransformation::CalculateDigest (
    this=0x7fffffffe820, digest=0x800253000 "", input=<optimized out>,
    length=192) at /usr/local/include/cryptopp/cryptlib.h:1189
No locals.

length=192 is wrong, if I am not mistaken.

When I look at frame 4, where 192 is passed to frame 3:

(gdb) f 4
#4  CryptoPP::PKCS12_PBKDF<CryptoPP::SHA256>::DeriveKey (this=<optimized out>,
    derived=0x7fffffffe9a0 "\320`\263", derivedLen=32,
    purpose=<optimized out>, secret=<optimized out>, secretLen=8,
    salt=0x7fffffffeac0 "salt", saltLen=4, iterations=1024, timeInSeconds=0)
    at /usr/local/include/cryptopp/pwdbased.h:439
439            hash.CalculateDigest(Ai, buffer, buffer.size());
(gdb) p Ai
$3 = {
  m_alloc = {<CryptoPP::AllocatorBase<unsigned char>> = {<No data
fields>}, <No data fields>}, m_mark = 18446744073709551615, m_size =
32,
  m_ptr = 0x800253000 ""}

So the size looks OK at frame 4.

On the upside, building Crypto++ 8.5 from sources is OK and tests OK.
I can't duplicate when using Crypto++ 8.5 or Master. It is OK with
both the static lib and shared lib.

I would be interested to know how FreeBSD builds the library. Like are
they using LTO, which is known bad. Every distro I have seen that uses
LTO has problems with it. Also see
https://cryptopp.com/wiki/Link_Time_Optimization.

Is there any chance you can avoid FreeBSD's version, and build
Crypto++ yourself?

Jeff

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