core: Do not crash if CMS plaintext is ignored

* src/engine-gpgsm.c (gpgsm_verify): Fix handling both
plaintext and signed_text as NULL.

--
Previously if plaintext was NULL and signed_text was NULL
it would set MESSAGE_FD to NULL which resulted in a
crash.

Ignoring the plaintext of an opaque signature might
make sense in some cases and engine-gpg handles it.

1 files changed, 11 insertions, 3 deletions

diff --git a/src/engine-gpgsm.c b/src/engine-gpgsm.c
index 3266e360..6e6df469 100644
--- a/src/engine-gpgsm.c
+++ b/src/engine-gpgsm.c
@@ -2030,11 +2030,19 @@ gpgsm_verify (void *engine, gpgme_data_t sig, gpgme_data_t signed_text,
   err = gpgsm_set_fd (gpgsm, INPUT_FD, map_data_enc (gpgsm->input_cb.data));
   if (err)
     return err;
-  if (plaintext)
+  if (!signed_text)
     {
       /* Normal or cleartext signature.  */
-      gpgsm->output_cb.data = plaintext;
-      err = gpgsm_set_fd (gpgsm, OUTPUT_FD, 0);
+      if (plaintext)
+        {
+          gpgsm->output_cb.data = plaintext;
+          err = gpgsm_set_fd (gpgsm, OUTPUT_FD, 0);
+        }
+      else
+        {
+          /* No output requested.  */
+          gpgsm_clear_fd (gpgsm, OUTPUT_FD);
+        }
       gpgsm_clear_fd (gpgsm, MESSAGE_FD);
     }
   else