Avoid double-free in vacuumlo error path.

The code would do "PQclear(res)" twice if lo_unlink failed, evidently
due to careless thinking about how far out a "break" would break.
Remove the extra PQclear and adjust the loop logic so that we'll fall
out of both levels of loop after an error, as was clearly the intent.

Spotted by Coverity.  I have no idea why it took this long to notice,
since the bug has been there since commit 67ccbb080.  Accordingly,
back-patch to all supported branches.

diff --git a/contrib/vacuumlo/vacuumlo.c b/contrib/vacuumlo/vacuumlo.c
index 10daa85445c24ff1a90e05eb8a01420a8e037a68..324c8dc07331a0f769367a75421541bada452b8f 100644 (file)
--- a/contrib/vacuumlo/vacuumlo.c
+++ b/contrib/vacuumlo/vacuumlo.c
@@ -302,7 +302,7 @@ vacuumlo(const char *database, const struct _param * param)
 
    deleted = 0;
 
-   while (1)
+   do
    {
        res = PQexec(conn, buf);
        if (PQresultStatus(res) != PGRES_TUPLES_OK)
@@ -340,8 +340,7 @@ vacuumlo(const char *database, const struct _param * param)
                    if (PQtransactionStatus(conn) == PQTRANS_INERROR)
                    {
                        success = false;
-                       PQclear(res);
-                       break;
+                       break;  /* out of inner for-loop */
                    }
                }
                else
@@ -379,7 +378,7 @@ vacuumlo(const char *database, const struct _param * param)
        }
 
        PQclear(res);
-   }
+   } while (success);
 
    /*
     * That's all folks!