MDEV-23092 SIGABRT when setting invalid wsrep_provider

Some invalid wsrep_provider paths may be interpreted as a valid
directory. For example '/invalid/libgalera_smm.so' with UTF character
set is interpreted as '/', which is a valid directory. A early check
that wsrep_provider should not be a directory fixes it.

1 files changed, 6 insertions, 0 deletions

diff --git a/sql/wsrep_var.cc b/sql/wsrep_var.cc
index 64362d1c9e2..3649153e172 100644
--- a/sql/wsrep_var.cc
+++ b/sql/wsrep_var.cc
@@ -320,6 +320,12 @@ static int wsrep_provider_verify (const char* provider_str)
   {
     return 1;
   }
+
+  if (MY_S_ISDIR(f_stat.st_mode))
+  {
+    return 1;
+  }
+
   return 0;
 }