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authorNeil Horman <nhorman@tuxdriver.com>2013-09-17 12:33:11 +0000
committerWilly Tarreau <w@1wt.eu>2014-05-19 07:54:32 +0200
commita35f8f7b89f6c91bae8aa46507556de4185e9e7a (patch)
tree1d50a46710d46dd2669f9aa4b45e0496fde4b805
parent1b3b362f84f5f2dd62d180447ba1a1681f5d993a (diff)
downloadlinux-linaro-stable-a35f8f7b89f6c91bae8aa46507556de4185e9e7a.tar.gz
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: Willy Tarreau <w@1wt.eu>
-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 3aa6e3834bfe..0ffd5995f30a 100644
--- a/crypto/ansi_cprng.c
+++ b/crypto/ansi_cprng.c
@@ -232,11 +232,11 @@ 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;
}