Ensure we check i2d_X509 return val

The i2d_X509() function can return a negative value on error. Therefore
we should make sure we check it.

Issue reported by Yuan Jochen Kang.

Reviewed-by: Emilia Käsper <emilia@openssl.org>
(cherry picked from commit 446ba8de9af9aa4fa3debc7c76a38f4efed47a62)

2 files changed, 19 insertions, 5 deletions

diff --git a/crypto/asn1/x_x509.c b/crypto/asn1/x_x509.c
index e2cac83694..ccdf6dfe13 100644
--- a/crypto/asn1/x_x509.c
+++ b/crypto/asn1/x_x509.c
@@ -201,10 +201,19 @@ X509 *d2i_X509_AUX(X509 **a, const unsigned char **pp, long length)
 
 int i2d_X509_AUX(X509 *a, unsigned char **pp)
 {
-    int length;
+    int length, tmplen;
+    unsigned char *start = *pp;
     length = i2d_X509(a, pp);
-    if (a)
-        length += i2d_X509_CERT_AUX(a->aux, pp);
+    if (length < 0 || a == NULL)
+        return length;
+
+    tmplen = i2d_X509_CERT_AUX(a->aux, pp);
+    if (tmplen < 0) {
+        *pp = start;
+        return tmplen;
+    }
+    length += tmplen;
+
     return length;
 }
 
diff --git a/ssl/ssl_cert.c b/ssl/ssl_cert.c
index acc5361544..f48ebaecc0 100644
--- a/ssl/ssl_cert.c
+++ b/ssl/ssl_cert.c
@@ -1059,13 +1059,18 @@ static int ssl_add_cert_to_buf(BUF_MEM *buf, unsigned long *l, X509 *x)
     unsigned char *p;
 
     n = i2d_X509(x, NULL);
-    if (!BUF_MEM_grow_clean(buf, (int)(n + (*l) + 3))) {
+    if (n < 0 || !BUF_MEM_grow_clean(buf, (int)(n + (*l) + 3))) {
         SSLerr(SSL_F_SSL_ADD_CERT_TO_BUF, ERR_R_BUF_LIB);
         return 0;
     }
     p = (unsigned char *)&(buf->data[*l]);
     l2n3(n, p);
-    i2d_X509(x, &p);
+    n = i2d_X509(x, &p);
+    if (n < 0) {
+        /* Shouldn't happen */
+        SSLerr(SSL_F_SSL_ADD_CERT_TO_BUF, ERR_R_BUF_LIB);
+        return 0;
+    }
     *l += n + 3;
 
     return 1;