Don't crash on a missing Subject in index.txt

An index.txt entry which has an empty Subject name field will cause ca
to crash. Therefore check it when we load it to make sure its not empty.

Fixes #5109

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5114)

1 files changed, 4 insertions, 0 deletions

diff --git a/apps/ca.c b/apps/ca.c
index 551d0aa2f8..9b1d9bdaac 100644
--- a/apps/ca.c
+++ b/apps/ca.c
@@ -663,6 +663,10 @@ end_of_options:
                 goto end;
             }
         }
+        if (pp[DB_name][0] == '\0') {
+            BIO_printf(bio_err, "entry %d: bad Subject\n", i + 1);
+            goto end;
+        }
     }
     if (verbose) {
         TXT_DB_write(bio_out, db->db);