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

[Bjorn Kornefalk 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).

Same errors at line 99
   data = (size_t *)counter;

The solution is either to change the implementation to work with bytes or 
to change the input vector to 
const size_t *in, 
size_t *out,
size_t ivec[16 / sizeof(size_t)],
size_t ecount_buf[16 / sizeof(size_t)

The workaround is to make sure that the input, output, ivvec and ecount 
are all aligned, but since they are declared as single byte arrays, there 
is a violation of the contract between input arguments and the usage of 
the arguments.



Example to provoke this error running 64-bit SunOS

core 'core' of 23520:   ../out/solaris/pnrg_test
 ffffffff7efa44b4 CRYPTO_ctr128_encrypt (10010a090, 10010b8c0, 10, 
ffffffff7fffef58, ffffffff7ffff128, ffffffff7ffff13c) + d8
 ffffffff7ef8dd80 AES_ctr128_encrypt (10010a090, 10010b8c0, 10, 
ffffffff7fffef58, ffffffff7ffff128, ffffffff7ffff13c) + 3c
 00000001000057ac PNRG::generateRandomData(unsigned long) 
(ffffffff7ffff13c, ffffffff7ffff128, 100, 20, 10010a090, 10010a0b0) + 13c



In Linux, it does not provoke a core dump.

Applicaition is compiled using

gcc (GCC) 4.9.2
Copyright (C) 2014 Free Software Foundation, Inc.

Best regards
  Björn Kornefalk
  Senior Software Engineer
  Giesecke & Devrient 3S AB
  Fredsborgsgatan 24
  100 74 Stockholm
  SWEDEN
  Tel: (+46) 70 350 5633
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