tree 8f376587cecb17c5122065c2d1012487dc7f897f
parent 759ef4fffbfdb7f7ebf7184228390c65075a4e4f
author Neil Horman <nhorman@tuxdriver.com> 1379421191 -0400
committer chrmhoffmann <chrmhoffmann@gmail.com> 1586074743 +0200

crypto: ansi_cprng - Fix off by one error in non-block size request

commit 714b33d15130cbb5ab426456d4e3de842d6c5b8a upstream.

Stephan Mueller reported to me recently a error in random number generation in
the ansi cprng. If several small requests are made that are less than the
instances block size, the remainder for loop code doesn't increment
rand_data_valid in the last iteration, meaning that the last bytes in the
rand_data buffer gets reused on the subsequent smaller-than-a-block request for
random data.

The fix is pretty easy, just re-code the for loop to make sure that
rand_data_valid gets incremented appropriately

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Reported-by: Stephan Mueller <stephan.mueller@atsec.com>
CC: Stephan Mueller <stephan.mueller@atsec.com>
CC: Petr Matousek <pmatouse@redhat.com>
CC: Herbert Xu <herbert@gondor.apana.org.au>
CC: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>