g10: Improve handling of no corresponding public key.

* g10/getkey.c (get_seckey): Return G10ERR_NO_PUBKEY when it's not
exact match.

--

(ported from 1.4 commit b3fd30451a5464b124b0296afbc341cb98b3977c)

In the situation of corrupted .gnupg/ where only private subkey is
available but no corresponding public key of the subkey, the code
returned public primary key which caused mysterious error (for a
user).  This fix detects an error earlier.

GnuPG-bug-id: 1422
Debian-Bug-Id: #638619

1 files changed, 12 insertions, 0 deletions

diff --git a/g10/getkey.c b/g10/getkey.c
index 8b3cf2d24..a27c8e28a 100644
--- a/g10/getkey.c
+++ b/g10/getkey.c
@@ -500,7 +500,19 @@ get_seckey( PKT_secret_key *sk, u32 *keyid )
     ctx.req_usage = sk->req_usage;
     rc = lookup( &ctx, &kb, 1 );
     if ( !rc ) {
+        u32 skid[2];
+
         sk_from_block ( &ctx, sk, kb );
+        keyid_from_sk ( sk, skid );
+        /*
+         * Make sure it's exact match of keyid.
+         * If not, it's secret subkey with no public key.
+         */
+        if (!(keyid[0] == skid[0] && keyid[1] == skid[1])) {
+          log_error (_("key %s: secret key without public key"
+                       " - skipped\n"), keystr(keyid));
+          rc = G10ERR_NO_PUBKEY;
+        }
     }
     get_seckey_end( &ctx );
     release_kbnode ( kb );