Fix OCSP_basic_verify signer certificate validation

The function `OCSP_basic_verify` validates the signer certificate on an OCSP response. The internal function, ocsp_verify_signer, is responsible for this and is expected to return a 0 value in the event of a failure to verify. Unfortunately, due to a bug, it actually returns with a postive success response in this case. In the normal course of events OCSP_basic_verify will then continue and will fail anyway in the ocsp_check_issuer function because the supplied "chain" value will be empty in the case that ocsp_verify_signer failed to verify the chain. This will cause OCSP_basic_verify to return with a negative result (fatal error). Normally in the event of a failure to verify it should return with 0. However, in the case of the OCSP_NOCHECKS flag being used, OCSP_basic_verify will return with a positvie result. This could lead to callers trusting an OCSP Basic response when it should not be. CVE-2022-1343 Fixes #18053 Reviewed-by: Paul Dale <pauli@openssl.org> Reviewed-by: Tomas Mraz <tomas@openssl.org> Reviewed-by: Matt Caswell <matt@openssl.org>
openssl · May 3, 2022 · 2eda987 · 2eda987
1 parent ae3ece0
commit 2eda987
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/crypto/ocsp/ocsp_vfy.c b/crypto/ocsp/ocsp_vfy.c
@@ -59,9 +59,10 @@ static int ocsp_verify_signer(X509 *signer, int response,
 
     ret = X509_verify_cert(ctx);
     if (ret <= 0) {
-        ret = X509_STORE_CTX_get_error(ctx);
+        int err = X509_STORE_CTX_get_error(ctx);
+
         ERR_raise_data(ERR_LIB_OCSP, OCSP_R_CERTIFICATE_VERIFY_ERROR,
-                       "Verify error: %s", X509_verify_cert_error_string(ret));
+                       "Verify error: %s", X509_verify_cert_error_string(err));
         goto end;
     }
     if (chain != NULL)