1 files changed, 2 insertions, 0 deletions
diff --git a/sm/certcheck.c b/sm/certcheck.c
index e8b842b88..efb1414cc 100644
--- a/sm/certcheck.c
+++ b/sm/certcheck.c
@@ -68,6 +68,8 @@ do_encode_md (gcry_md_hd_t md, int algo, int pkalgo, unsigned int nbits,
       nframe = (nbits+7) / 8;
 
       asnlen = DIM(asn);
+      if (!algo || gcry_md_test_algo (algo))
+        return gpg_error (GPG_ERR_DIGEST_ALGO);
       if (gcry_md_algo_info (algo, GCRYCTL_GET_ASNOID, asn, &asnlen))
         {
           log_error ("no object identifier for algo %d\n", algo);