Add error handling in dsa_main and ASN1_i2d_bio.

CLA: trivial
Reviewed-by: NKurt Roeckx <kurt@roeckx.be>
Reviewed-by: NBernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/4600)

apps/dsa.c

@@ -217,6 +217,9 @@ int dsa_main(int argc, char **argv)
     } else if (outformat == FORMAT_MSBLOB || outformat == FORMAT_PVK) {
         EVP_PKEY *pk;
         pk = EVP_PKEY_new();
+        if (pk == NULL)
+           goto end;
+
         EVP_PKEY_set1_DSA(pk, dsa);
         if (outformat == FORMAT_PVK) {
             if (pubin) {

crypto/asn1/a_i2d_fp.c

@@ -38,6 +38,9 @@ int ASN1_i2d_bio(i2d_of_void *i2d, BIO *out, unsigned char *x)
     int i, j = 0, n, ret = 1;
 
     n = i2d(x, NULL);
+    if (n <= 0)
+        return 0;
+
     b = OPENSSL_malloc(n);
     if (b == NULL) {
         ASN1err(ASN1_F_ASN1_I2D_BIO, ERR_R_MALLOC_FAILURE);