[git] GnuPG - branch, STABLE-BRANCH-2-2, updated. gnupg-2.2.5-27-g456a3a8

[by Werner Koch]

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- Log -----------------------------------------------------------------
commit 456a3a8e93ea14f821e0e98fb515f284ece98685
Author: Werner Koch <wk at gnupg.org>
Date:   Mon Mar 26 16:57:04 2018 +0200

    gpg: Fix trustdb updates without lock held.
    
    * g10/tdbio.c (is_locked): Turn into a counter.
    (take_write_lock, release_write_lock): Implement recursive locks.
    --
    
    On trustdb creation we have this call sequence:
    
      init_trustdb                 -> takes lock
        tdbio_set_dbname
          create_version_record
           tdbio_write_record
             put_record_into_cache -> takes lock
             put_record_into_cache -> releases lock
      init_trustdb                 -> releases lock
    
    The second take lock does noting but the first release lock has
    already released the lock and the second release lock is a thus a NOP.
    This is likely the cause for the corrupted trustdb as reported in
    
    GnuPG-bug-id: 3839
    Signed-off-by: Werner Koch <wk at gnupg.org>

diff --git a/g10/tdbio.c b/g10/tdbio.c
index fb3cf15..4940c5c 100644
--- a/g10/tdbio.c
+++ b/g10/tdbio.c
@@ -105,10 +105,11 @@ struct cmp_xdir_struct
 /* The name of the trustdb file.  */
 static char *db_name;
 
-/* The handle for locking the trustdb file and a flag to record
-   whether a lock has been taken.  */
+/* The handle for locking the trustdb file and a counter to record how
+ * often this lock has been taken.  That counter is required becuase
+ * dotlock does not implemen recursive locks.  */
 static dotlock_t lockhandle;
-static int is_locked;
+static unsigned int is_locked;
 
 /* The file descriptor of the trustdb.  */
 static int  db_fd = -1;
@@ -135,6 +136,8 @@ static void create_hashtable (ctrl_t ctrl, TRUSTREC *vr, int type);
 static int
 take_write_lock (void)
 {
+  int rc;
+
   if (!lockhandle)
     lockhandle = dotlock_create (db_name, 0);
   if (!lockhandle)
@@ -144,12 +147,16 @@ take_write_lock (void)
     {
       if (dotlock_take (lockhandle, -1) )
         log_fatal ( _("can't lock '%s'\n"), db_name );
-      else
-        is_locked = 1;
-      return 0;
+      rc = 0;
     }
   else
-    return 1;
+    rc = 1;
+
+  if (opt.lock_once)
+    is_locked = 1;
+  else
+    is_locked++;
+  return rc;
 }
 
 
@@ -160,10 +167,22 @@ take_write_lock (void)
 static void
 release_write_lock (void)
 {
-  if (!opt.lock_once)
-    if (!dotlock_release (lockhandle))
-      is_locked = 0;
+  if (opt.lock_once)
+    return;  /* Don't care; here IS_LOCKED is fixed to 1.  */
+
+  if (!is_locked)
+    {
+      log_error ("Ooops, tdbio:release_write_lock with no lock held\n");
+      return;
+    }
+  if (--is_locked)
+    return;
+
+  if (dotlock_release (lockhandle))
+    log_error ("Oops, tdbio:release_write_locked failed\n");
 }
+
+
 

 /*************************************
  ************* record cache **********

commit 5f00531463ebc0e606c502696962426007545bb7
Author: Werner Koch <wk at gnupg.org>
Date:   Mon Mar 26 16:26:46 2018 +0200

    gpg: Disable unused code parts in tdbio.c
    
    * g10/tdbio.c (in_transaction): Comment this var.
    (put_record_into_cache): Comment the transaction code.
    (tdbio_sync): Ditto
    
    Signed-off-by: Werner Koch <wk at gnupg.org>

diff --git a/g10/tdbio.c b/g10/tdbio.c
index 7572b9a..fb3cf15 100644
--- a/g10/tdbio.c
+++ b/g10/tdbio.c
@@ -114,7 +114,7 @@ static int is_locked;
 static int  db_fd = -1;
 
 /* A flag indicating that a transaction is active.  */
-static int in_transaction;
+/* static int in_transaction;   Not yet used. */
 
 
 

@@ -125,7 +125,7 @@ static void create_hashtable (ctrl_t ctrl, TRUSTREC *vr, int type);
 

 /*
  * Take a lock on the trustdb file name.  I a lock file can't be
- * created the function terminates the process.  Excvept for a
+ * created the function terminates the process.  Except for a
  * different return code the function does nothing if the lock has
  * already been taken.
  *
@@ -329,6 +329,7 @@ put_record_into_cache (ulong recno, const char *data)
     }
 
   /* No clean entries: We have to flush some dirty entries.  */
+#if 0 /* Transactions are not yet used.  */
   if (in_transaction)
     {
       /* But we can't do this while in a transaction.  Thus we
@@ -352,6 +353,7 @@ put_record_into_cache (ulong recno, const char *data)
       log_info (_("trustdb transaction too large\n"));
       return GPG_ERR_RESOURCE_LIMIT;
     }
+#endif
 
   if (dirty_count)
     {
@@ -418,8 +420,10 @@ tdbio_sync()
 
     if( db_fd == -1 )
 	open_db();
+#if 0 /* Transactions are not yet used.  */
     if( in_transaction )
 	log_bug("tdbio: syncing while in transaction\n");
+#endif
 
     if( !cache_is_dirty )
 	return 0;
@@ -560,7 +564,7 @@ tdbio_update_version_record (ctrl_t ctrl)
 
 /*
  * Create and write the trustdb version record.
- *
+ * This is called with the writelock activ.
  * Returns: 0 on success or an error code.
  */
 static int

-----------------------------------------------------------------------

Summary of changes:
 g10/tdbio.c | 49 ++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 36 insertions(+), 13 deletions(-)


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