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authorNeil Horman <nhorman@tuxdriver.com>2013-09-17 08:33:11 -0400
committerHerbert Xu <herbert@gondor.apana.org.au>2013-09-24 06:02:23 +1000
commit714b33d15130cbb5ab426456d4e3de842d6c5b8a (patch)
tree038690f74a44de6a5c6604e5732aa05633773e6f /crypto
parentec795ad84c0a8c69723972eae31e60b0d94ab29a (diff)
downloadlinux-linaro-stable-714b33d15130cbb5ab426456d4e3de842d6c5b8a.tar.gz
crypto: ansi_cprng - Fix off by one error in non-block size request
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>
Diffstat (limited to 'crypto')
-rw-r--r--crypto/ansi_cprng.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c
index c0bb3778f1ae..666f1962a160 100644
--- a/crypto/ansi_cprng.c
+++ b/crypto/ansi_cprng.c
@@ -230,11 +230,11 @@ remainder:
*/
if (byte_count < DEFAULT_BLK_SZ) {
empty_rbuf:
- for (; ctx->rand_data_valid < DEFAULT_BLK_SZ;
- ctx->rand_data_valid++) {
+ while (ctx->rand_data_valid < DEFAULT_BLK_SZ) {
*ptr = ctx->rand_data[ctx->rand_data_valid];
ptr++;
byte_count--;
+ ctx->rand_data_valid++;
if (byte_count == 0)
goto done;
}