Another libsepol USE_AFTER_FREE defects detected

[Petr Lautrbach <plautrba@redhat.com>]

Hello,

our internal scanner reports the following defects:

Error: USE_AFTER_FREE (CWE-416): [#def1]
libsepol/cil/src/cil_build_ast.c:473: freed_arg: "cil_gen_node" frees "class".
libsepol/cil/src/cil_build_ast.c:480: deref_after_free: Dereferencing freed pointer "class".
#  478|   	if (parse_current->next->next != NULL) {
#  479|   		perms = parse_current->next->next->cl_head;
#  480|-> 		rc = cil_gen_perm_nodes(db, perms, ast_node, CIL_PERM, &class->num_perms);
#  481|   		if (rc != SEPOL_OK) {
#  482|   			goto exit;

Error: USE_AFTER_FREE (CWE-416): [#def2]
libsepol/cil/src/cil_build_ast.c:942: freed_arg: "cil_gen_node" frees "map".
libsepol/cil/src/cil_build_ast.c:947: deref_after_free: Dereferencing freed pointer "map".
#  945|   	}
#  946|   
#  947|-> 	rc = cil_gen_perm_nodes(db, parse_current->next->next->cl_head, ast_node, CIL_MAP_PERM, &map->num_perms);
#  948|   	if (rc != SEPOL_OK) {
#  949|   		goto exit;

Error: USE_AFTER_FREE (CWE-416): [#def3]
libsepol/cil/src/cil_build_ast.c:1042: freed_arg: "cil_gen_node" frees "common".
libsepol/cil/src/cil_build_ast.c:1047: deref_after_free: Dereferencing freed pointer "common".
# 1045|   	}
# 1046|   
# 1047|-> 	rc = cil_gen_perm_nodes(db, parse_current->next->next->cl_head, ast_node, CIL_PERM, &common->num_perms);
# 1048|   	if (rc != SEPOL_OK) {
# 1049|   		goto exit;


They might be related to commit 0d4e568afe5a28edc5fcdcff8e925d4ec1d0d3d0
("libsepol/cil: Create function cil_add_decl_to_symtab() and refactor")

Please take a look.

Thanks,

Petr