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authorNeil Horman <nhorman@tuxdriver.com>2013-09-17 08:33:11 -0400
committerBen Hutchings <ben@decadent.org.uk>2014-01-03 04:33:35 +0000
commitd1b8de7813fc2127dc16cd9f282bb63611583997 (patch)
treea7867265bd8798dfa0967a57e0866bce190c1929 /crypto
parent0b568069764b25b7114b241c361a904838280639 (diff)
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> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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 ffa0245e2abc..6056178453c4 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;
}