From a35f8f7b89f6c91bae8aa46507556de4185e9e7a Mon Sep 17 00:00:00 2001 From: Neil Horman Date: Tue, 17 Sep 2013 12:33:11 +0000 Subject: 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 Reported-by: Stephan Mueller CC: Stephan Mueller CC: Petr Matousek CC: Herbert Xu CC: "David S. Miller" Signed-off-by: Herbert Xu Signed-off-by: Willy Tarreau --- crypto/ansi_cprng.c | 4 ++-- 1 file 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; } -- cgit v1.2.3