Fix dereference of null pointer which Clang Static Analyser pointed out.

diff --git a/libarchive/archive_write_set_format_mtree.c b/libarchive/archive_write_set_format_mtree.c
index 4d343eaf212dbcdf373688f9d3f729c459f45500..3e97adc5bda8af0d0f172cc7453732efb07aefa0 100644 (file)
--- a/libarchive/archive_write_set_format_mtree.c
+++ b/libarchive/archive_write_set_format_mtree.c
@@ -639,7 +639,7 @@ attr_counter_inc(struct attr_counter **top, struct attr_counter *ac,
                        *top = ac;
                        ac->next->prev = ac;
                }
-       } else {
+       } else if (last != NULL) {
                ac = attr_counter_new(me, last);
                if (ac == NULL)
                        return (-1);