If we decide to discard the provided seed buffer because its size is not

large enough, do it correctly so that the local seed buffer on the stack
gets properly initialized in the first iteration of the loop.
While there, remove an outdated and bogus comment.
Coverity CID 21785
ok doug@ jsing@

2 files changed, 12 insertions, 16 deletions

diff --git a/src/lib/libcrypto/dsa/dsa_gen.c b/src/lib/libcrypto/dsa/dsa_gen.c
index dcfa957884..c1664d5f8a 100644
--- a/src/lib/libcrypto/dsa/dsa_gen.c
+++ b/src/lib/libcrypto/dsa/dsa_gen.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: dsa_gen.c,v 1.18 2015/02/09 15:49:22 jsing Exp $ */
+/* $OpenBSD: dsa_gen.c,v 1.19 2015/02/15 08:48:24 miod Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -126,12 +126,10 @@ dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits, const EVP_MD *evpmd,
 
         bits = (bits + 63) / 64 * 64;
 
-        /*
-         * NB: seed_len == 0 is special case: copy generated seed to
-         * seed_in if it is not NULL.
-         */
-        if (seed_len && seed_len < (size_t)qsize)
+        if (seed_len < (size_t)qsize) {
                 seed_in = NULL;         /* seed buffer too small -- ignore */
+                seed_len = 0;
+        }
         /*
          * App. 2.2 of FIPS PUB 186 allows larger SEED,
          * but our internal buffers are restricted to 160 bits
@@ -176,7 +174,7 @@ dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits, const EVP_MD *evpmd,
                         if (!BN_GENCB_call(cb, 0, m++))
                                 goto err;
 
-                        if (!seed_len) {
+                        if (seed_len == 0) {
                                 arc4random_buf(seed, qsize);
                                 seed_is_random = 1;
                         } else {
@@ -344,7 +342,7 @@ err:
                         *counter_ret = counter;
                 if (h_ret != NULL)
                         *h_ret = h;
-                if (seed_out)
+                if (seed_out != NULL)
                         memcpy(seed_out, seed, qsize);
         }
         if (ctx) {
diff --git a/src/lib/libssl/src/crypto/dsa/dsa_gen.c b/src/lib/libssl/src/crypto/dsa/dsa_gen.c
index dcfa957884..c1664d5f8a 100644
--- a/src/lib/libssl/src/crypto/dsa/dsa_gen.c
+++ b/src/lib/libssl/src/crypto/dsa/dsa_gen.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: dsa_gen.c,v 1.18 2015/02/09 15:49:22 jsing Exp $ */
+/* $OpenBSD: dsa_gen.c,v 1.19 2015/02/15 08:48:24 miod Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -126,12 +126,10 @@ dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits, const EVP_MD *evpmd,
 
         bits = (bits + 63) / 64 * 64;
 
-        /*
-         * NB: seed_len == 0 is special case: copy generated seed to
-         * seed_in if it is not NULL.
-         */
-        if (seed_len && seed_len < (size_t)qsize)
+        if (seed_len < (size_t)qsize) {
                 seed_in = NULL;         /* seed buffer too small -- ignore */
+                seed_len = 0;
+        }
         /*
          * App. 2.2 of FIPS PUB 186 allows larger SEED,
          * but our internal buffers are restricted to 160 bits
@@ -176,7 +174,7 @@ dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits, const EVP_MD *evpmd,
                         if (!BN_GENCB_call(cb, 0, m++))
                                 goto err;
 
-                        if (!seed_len) {
+                        if (seed_len == 0) {
                                 arc4random_buf(seed, qsize);
                                 seed_is_random = 1;
                         } else {
@@ -344,7 +342,7 @@ err:
                         *counter_ret = counter;
                 if (h_ret != NULL)
                         *h_ret = h;
-                if (seed_out)
+                if (seed_out != NULL)
                         memcpy(seed_out, seed, qsize);
         }
         if (ctx) {