Fix seg fault in TS_RESP_verify_response()

The TS_RESP_verify_response() function is used for verifying the response
from a TSA. You can set the provided TS_VERIFY_CTX with different flags
depending on what aspects of the response you wish to verify.

A seg fault will occur if you supply the TS_VFY_SIGNER or TS_VFY_TSA_NAME
flags without also specifying TS_VFY_SIGNATURE.

Reviewed-by: Rich Salz <rsalz@openssl.org>

1 files changed, 15 insertions, 8 deletions

diff --git a/crypto/ts/ts_rsp_verify.c b/crypto/ts/ts_rsp_verify.c
index 29aa5a497e..97d9c81db6 100644
--- a/crypto/ts/ts_rsp_verify.c
+++ b/crypto/ts/ts_rsp_verify.c
@@ -434,51 +434,58 @@ static int int_TS_RESP_verify_token(TS_VERIFY_CTX *ctx,
     unsigned char *imprint = NULL;
     unsigned imprint_len = 0;
     int ret = 0;
+    int flags = ctx->flags;
+
+    /* Some options require us to also check the signature */
+    if (((flags & TS_VFY_SIGNER) && tsa_name != NULL)
+            || (flags & TS_VFY_TSA_NAME)) {
+        flags |= TS_VFY_SIGNATURE;
+    }
 
     /* Verify the signature. */
-    if ((ctx->flags & TS_VFY_SIGNATURE)
+    if ((flags & TS_VFY_SIGNATURE)
         && !TS_RESP_verify_signature(token, ctx->certs, ctx->store, &signer))
         goto err;
 
     /* Check version number of response. */
-    if ((ctx->flags & TS_VFY_VERSION)
+    if ((flags & TS_VFY_VERSION)
         && TS_TST_INFO_get_version(tst_info) != 1) {
         TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_UNSUPPORTED_VERSION);
         goto err;
     }
 
     /* Check policies. */
-    if ((ctx->flags & TS_VFY_POLICY)
+    if ((flags & TS_VFY_POLICY)
         && !TS_check_policy(ctx->policy, tst_info))
         goto err;
 
     /* Check message imprints. */
-    if ((ctx->flags & TS_VFY_IMPRINT)
+    if ((flags & TS_VFY_IMPRINT)
         && !TS_check_imprints(ctx->md_alg, ctx->imprint, ctx->imprint_len,
                               tst_info))
         goto err;
 
     /* Compute and check message imprints. */
-    if ((ctx->flags & TS_VFY_DATA)
+    if ((flags & TS_VFY_DATA)
         && (!TS_compute_imprint(ctx->data, tst_info,
                                 &md_alg, &imprint, &imprint_len)
             || !TS_check_imprints(md_alg, imprint, imprint_len, tst_info)))
         goto err;
 
     /* Check nonces. */
-    if ((ctx->flags & TS_VFY_NONCE)
+    if ((flags & TS_VFY_NONCE)
         && !TS_check_nonces(ctx->nonce, tst_info))
         goto err;
 
     /* Check whether TSA name and signer certificate match. */
-    if ((ctx->flags & TS_VFY_SIGNER)
+    if ((flags & TS_VFY_SIGNER)
         && tsa_name && !TS_check_signer_name(tsa_name, signer)) {
         TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_TSA_NAME_MISMATCH);
         goto err;
     }
 
     /* Check whether the TSA is the expected one. */
-    if ((ctx->flags & TS_VFY_TSA_NAME)
+    if ((flags & TS_VFY_TSA_NAME)
         && !TS_check_signer_name(ctx->tsa_name, signer)) {
         TSerr(TS_F_INT_TS_RESP_VERIFY_TOKEN, TS_R_TSA_UNTRUSTED);
         goto err;