[PATCH] libsepol/cil: fix NULL pointer dereference in cil_fill_ipaddr

[lutianxiong <lutianxiong@xxxxxxxxxx>]

Found a NULL pointer dereference by fuzzing, reproducing:
    $ echo "(nodecon(())o(e()))" > tmp.cil
    $ secilc tmp.cil
    Segmentation fault (core dumped)

Add NULL check for addr_node->data in cil_fill_ipaddr.

Signed-off-by: lutianxiong <lutianxiong@xxxxxxxxxx>
---
 libsepol/cil/src/cil_build_ast.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libsepol/cil/src/cil_build_ast.c b/libsepol/cil/src/cil_build_ast.c
index 726f46c..4e53f06 100644
--- a/libsepol/cil/src/cil_build_ast.c
+++ b/libsepol/cil/src/cil_build_ast.c
@@ -5660,7 +5660,7 @@ int cil_fill_ipaddr(struct cil_tree_node *addr_node, struct cil_ipaddr *addr)
 {
 	int rc = SEPOL_ERR;
 
-	if (addr_node == NULL || addr == NULL) {
+	if (addr_node == NULL || addr_node->data == NULL || addr == NULL) {
 		goto exit;
 	}
 
-- 
2.23.0