Don't leak malloc'd error string in libpqrcv_check_conninfo().

We leaked the error report from PQconninfoParse, when there was
one.  It seems unlikely that real usage patterns would repeat
the failure often enough to create serious bloat, but let's
back-patch anyway to keep the code similar in all branches.

Found via valgrind testing.
Back-patch to v10 where this code was added.

Discussion: https://postgr.es/m/3816764.1616104288@sss.pgh.pa.us

diff --git a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
index f74378110a0082eb95ada92031c7f6ba1bd112b6..021c1b36f3ecbd3efa70b3be36e0a08d6081dc86 100644 (file)
--- a/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
+++ b/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
@@ -246,9 +246,15 @@ libpqrcv_check_conninfo(const char *conninfo)
 
        opts = PQconninfoParse(conninfo, &err);
        if (opts == NULL)
+       {
+               /* The error string is malloc'd, so we must free it explicitly */
+               char       *errcopy = err ? pstrdup(err) : "out of memory";
+
+               PQfreemem(err);
                ereport(ERROR,
                                (errcode(ERRCODE_SYNTAX_ERROR),
-                                errmsg("invalid connection string syntax: %s", err)));
+                                errmsg("invalid connection string syntax: %s", errcopy)));
+       }
 
        PQconninfoFree(opts);
 }