fuzz/asn1.c: Add missing check for BIO_new

Since the BIO_new may fail, the 'bio' could be NULL pointer and be used.
Therefore, it should be better to check it and skip the print if fails.
Signed-off-by: NJiasheng Jiang <jiasheng@iscas.ac.cn>
Reviewed-by: NTomas Mraz <tomas@openssl.org>
Reviewed-by: NPaul Dale <pauli@openssl.org>
Reviewed-by: NMatthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/17690)

fuzz/asn1.c

@@ -218,8 +218,10 @@ static ASN1_PCTX *pctx;
         int len2; \
         BIO *bio = BIO_new(BIO_s_null()); \
         \
-        PRINT(bio, type); \
-        BIO_free(bio); \
+        if (bio != NULL) { \
+            PRINT(bio, type); \
+            BIO_free(bio); \
+        } \
         len2 = I2D(type, &der); \
         if (len2 != 0) {} \
         OPENSSL_free(der); \
@@ -235,8 +237,10 @@ static ASN1_PCTX *pctx;
     if (type != NULL) { \
         BIO *bio = BIO_new(BIO_s_null()); \
         \
-        PRINT(bio, type, 0); \
-        BIO_free(bio); \
+        if (bio != NULL) { \
+            PRINT(bio, type, 0); \
+            BIO_free(bio); \
+        } \
         I2D(type, &der); \
         OPENSSL_free(der); \
         TYPE ## _free(type); \
@@ -251,8 +255,10 @@ static ASN1_PCTX *pctx;
     if (type != NULL) { \
         BIO *bio = BIO_new(BIO_s_null()); \
         \
-        PRINT(bio, type, 0, pctx); \
-        BIO_free(bio); \
+        if (bio != NULL) { \
+            PRINT(bio, type, 0, pctx); \
+            BIO_free(bio); \
+        } \
         I2D(type, &der); \
         OPENSSL_free(der); \
         TYPE ## _free(type); \
@@ -307,9 +313,10 @@ int FuzzerTestOneInput(const uint8_t *buf, size_t len)
 
         if (o != NULL) {
             BIO *bio = BIO_new(BIO_s_null());
-
-            ASN1_item_print(bio, o, 4, i, pctx);
-            BIO_free(bio);
+            if (bio != NULL) {
+                ASN1_item_print(bio, o, 4, i, pctx);
+                BIO_free(bio);
+            }
             ASN1_item_i2d(o, &der, i);
             OPENSSL_free(der);
             ASN1_item_free(o, i);