Add some sanity checks when checking CRL scores

Note: this was accidentally omitted from OpenSSL 1.0.2 branch. Without this fix any attempt to use CRLs will crash. CVE-2016-7052 Thanks to Bruce Stephens and Thomas Jakobi for reporting this issue. Reviewed-by: Stephen Henson <steve@openssl.org> Reviewed-by: Rich Salz <rsalz@openssl.org>
openssl · Sep 26, 2016 · 6e629b5 · 6e629b5
1 parent f15a7e3
commit 6e629b5
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/crypto/x509/x509_vfy.c b/crypto/x509/x509_vfy.c
@@ -1124,10 +1124,10 @@ static int get_crl_sk(X509_STORE_CTX *ctx, X509_CRL **pcrl, X509_CRL **pdcrl,
         crl = sk_X509_CRL_value(crls, i);
         reasons = *preasons;
         crl_score = get_crl_score(ctx, &crl_issuer, &reasons, crl, x);
-        if (crl_score < best_score)
+        if (crl_score < best_score || crl_score == 0)
             continue;
         /* If current CRL is equivalent use it if it is newer */
-        if (crl_score == best_score) {
+        if (crl_score == best_score && best_crl != NULL) {
             int day, sec;
             if (ASN1_TIME_diff(&day, &sec, X509_CRL_get_lastUpdate(best_crl),
                                X509_CRL_get_lastUpdate(crl)) == 0)