isl_convex_hull.c: isl_basic_set_add_equality: avoid NULL pointer dereference

diff --git a/isl_convex_hull.c b/isl_convex_hull.c
index 4a82e6a..cf3cfbf 100644 (file)
--- a/isl_convex_hull.c
+++ b/isl_convex_hull.c
@@ -213,6 +213,9 @@ static struct isl_basic_set *isl_basic_set_add_equality(
        int i;
        unsigned dim;
 
+       if (!bset)
+               return NULL;
+
        if (ISL_F_ISSET(bset, ISL_BASIC_SET_EMPTY))
                return bset;