xtables: set custom opts to NULL on free

When inside ip6tables-restore, xtables_free_opts can be called
multiple times, especially when trying to exit with an error message
from outside do_command. So set it to NULL so that we do not attempt
to free a dangling pointer.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>

1 files changed, 3 insertions, 1 deletions

diff --git a/xtables.c b/xtables.c
index 00362992..be103d75 100644
--- a/xtables.c
+++ b/xtables.c
@@ -75,8 +75,10 @@ void basic_exit_err(enum xtables_exittype status, const char *msg, ...)
 
 void xtables_free_opts(int unused)
 {
-	if (xt_params->opts != xt_params->orig_opts)
+	if (xt_params->opts != xt_params->orig_opts) {
 		free(xt_params->opts);
+		xt_params->opts = NULL;
+	}
 }
 
 struct option *xtables_merge_options(struct option *orig_opts,