[openssl-dev] [openssl.org #4218] Invalid typecasting in CRYPTO_ctr128_encrypt

[Andy Polyakov via RT]

>>> OpenSSL 1.0.2e
>>>
>>> At line 156 of crypto/modes/ctr128.c
>>>
>>> const unsigned char *in, 
>>> unsigned char *out,
>>> unsigned char ivec[16],
>>> unsigned char ecount_buf[16]
>>>
>>>    *(size_t *)(out + n) =
>>>        *(size_t *)(in + n) ^ *(size_t *)(ecount_buf + n);
>>>
>>> If the buffers are not aligned, the application crashes due to the invalid 
>>> type casting of unsigned char (1 byte) to size_t (4 to 8 bytes for most 
>>> CPU:s).
>>
>> You should not run into that issue if STRICT_ALIGNMENT is defined.
> 
> Well, yes, except that it doesn't check for alignment of ecount_buf. I
> mean there is 'if' clause for STRICT_ALIGNMENT that ensures that in, out
> and ivec are aligned, but not ecount_buf. And judging from crash report,
> it is ecount_buf that is not properly aligned (see last displayed
> argument). So that original analysis is sane. It should be noted that it
> looks like subroutine in question is called from application directly.
> While if called from EVP, i.e. the usual way, the problem never occurs,
> because that buffer is properly aligned within EVP_CIPHER_CTX structure.
> Resolution will follow later...

http://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=5e4bbeb49fb6522d858703201b5adee9611e7b7b.
Closing ticket.



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