Crash with parameter passing in crypto_aead_aes256gcm_decrypt and crypto_aead_chacha20poly1305_ietf_decrypt

[andreasbaumann]

Tests fail on 32-bit Intel:

==> Starting check()...
test_gcm_aead (unit.test_aead.TestAEAD) ... /startdir/PKGBUILD: line 30:   424 Aborted                 (core dumped) python -m unittest discover --start-directory tests -v
==> ERROR: A failure occurred in check().
    Aborting...

In sodium/crypto_aead_aes256gcm.h I see that mlen_p is a pointer to a 64-bit long long:

int crypto_aead_aes256gcm_decrypt(unsigned char *m,
                                  unsigned long long *mlen_p,
                                  unsigned char *nsec,
                                  const unsigned char *c,
                                  unsigned long long clen,
                                  const unsigned char *ad,
                                  unsigned long long adlen,
                                  const unsigned char *npub,
                                  const unsigned char *k)

In __init.py__ in the 'ctypes' wrapper I see:

mlen = ctypes.c_ulonglong()
..
   ret = nacl.crypto_aead_aes256gcm_decrypt(
        m, mlen,
        None,
        ctxt, ctypes.c_ulonglong(len(ctxt)),
        aad, ctypes.c_ulonglong(len(aad)),
        nonce, key)
...
    ret = nacl.crypto_aead_chacha20poly1305_ietf_decrypt(
        m, mlen,
        None,
        ctxt, ctypes.c_ulonglong(len(ctxt)),
        aad, ctypes.c_ulonglong(len(aad)),
        nonce, key)
...

This works fine on 64-bit, but not on 32-bit. The tests crash with segfault.

When I change the calls to use a ctypes.byref the tests work fine:

    ret = nacl.crypto_aead_aes256gcm_decrypt(
        m, ctypes.byref(mlen),
        None,
        ctxt, ctypes.c_ulonglong(len(ctxt)),
        aad, ctypes.c_ulonglong(len(aad)),
        nonce, key)
...
   ret = nacl.crypto_aead_chacha20poly1305_ietf_decrypt(
        m, ctypes.byref(mlen),
        None,
        ctxt, ctypes.c_ulonglong(len(ctxt)),
        aad, ctypes.c_ulonglong(len(aad)),
        nonce, key)

See also debugging session on https://bbs.archlinux32.org/viewtopic.php?pid=219#p219.

[andreasbaumann]

merged pull request