1 /* UndefinedBehaviorSanitizer, undefined behavior detector.
2 Copyright (C) 2014-2017 Free Software Foundation, Inc.
3 Contributed by Jakub Jelinek <jakub@redhat.com>
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
28 /* Test if we should instrument vptr access. */
31 cp_ubsan_instrument_vptr_p (tree type
)
33 if (!flag_rtti
|| flag_sanitize_undefined_trap_on_error
)
36 if (!sanitize_flags_p (SANITIZE_VPTR
))
41 type
= TYPE_MAIN_VARIANT (type
);
42 if (!CLASS_TYPE_P (type
) || !CLASSTYPE_VTABLES (type
))
49 /* Helper function for
50 cp_ubsan_maybe_instrument_{member_{call,access},downcast}.
51 Instrument vptr access. */
54 cp_ubsan_instrument_vptr (location_t loc
, tree op
, tree type
, bool is_addr
,
55 enum ubsan_null_ckind ckind
)
57 type
= TYPE_MAIN_VARIANT (type
);
58 const char *mangled
= mangle_type_string (type
);
59 hashval_t str_hash1
= htab_hash_string (mangled
);
60 hashval_t str_hash2
= iterative_hash (mangled
, strlen (mangled
), 0);
61 tree str_hash
= wide_int_to_tree (uint64_type_node
,
62 wi::uhwi (((uint64_t) str_hash1
<< 32)
65 op
= build_fold_addr_expr_loc (loc
, op
);
67 tree vptr
= fold_build3_loc (loc
, COMPONENT_REF
,
68 TREE_TYPE (TYPE_VFIELD (type
)),
69 build_fold_indirect_ref_loc (loc
, op
),
70 TYPE_VFIELD (type
), NULL_TREE
);
71 vptr
= fold_convert_loc (loc
, pointer_sized_int_node
, vptr
);
72 vptr
= fold_convert_loc (loc
, uint64_type_node
, vptr
);
73 if (ckind
== UBSAN_DOWNCAST_POINTER
)
75 tree cond
= build2_loc (loc
, NE_EXPR
, boolean_type_node
, op
,
76 build_zero_cst (TREE_TYPE (op
)));
77 /* This is a compiler generated comparison, don't emit
78 e.g. -Wnonnull-compare warning for it. */
79 TREE_NO_WARNING (cond
) = 1;
80 vptr
= build3_loc (loc
, COND_EXPR
, uint64_type_node
, cond
,
81 vptr
, build_int_cst (uint64_type_node
, 0));
83 tree ti_decl
= get_tinfo_decl (type
);
85 tree ptype
= build_pointer_type (type
);
87 = build_call_expr_internal_loc (loc
, IFN_UBSAN_VPTR
,
88 void_type_node
, 5, op
, vptr
, str_hash
,
89 build_address (ti_decl
),
90 build_int_cst (ptype
, ckind
));
91 TREE_SIDE_EFFECTS (call
) = 1;
92 return fold_build2 (COMPOUND_EXPR
, TREE_TYPE (op
), call
, op
);
95 /* Helper function for
96 cp_ubsan_maybe_instrument_{member_{call,access},downcast}.
97 Instrument vptr access if it should be instrumented, otherwise return
101 cp_ubsan_maybe_instrument_vptr (location_t loc
, tree op
, tree type
,
102 bool is_addr
, enum ubsan_null_ckind ckind
)
104 if (!cp_ubsan_instrument_vptr_p (type
))
106 return cp_ubsan_instrument_vptr (loc
, op
, type
, is_addr
, ckind
);
109 /* Instrument a member call (but not constructor call) if needed. */
112 cp_ubsan_maybe_instrument_member_call (tree stmt
)
114 if (call_expr_nargs (stmt
) == 0)
116 tree
*opp
= &CALL_EXPR_ARG (stmt
, 0);
118 if (op
== error_mark_node
119 || !POINTER_TYPE_P (TREE_TYPE (op
)))
121 while (TREE_CODE (op
) == COMPOUND_EXPR
)
123 opp
= &TREE_OPERAND (op
, 1);
126 op
= cp_ubsan_maybe_instrument_vptr (EXPR_LOCATION (stmt
), op
,
127 TREE_TYPE (TREE_TYPE (op
)),
128 true, UBSAN_MEMBER_CALL
);
133 /* Data passed to cp_ubsan_check_member_access_r. */
135 struct cp_ubsan_check_member_access_data
137 hash_set
<tree
> *pset
;
141 static tree
cp_ubsan_check_member_access_r (tree
*, int *, void *);
143 /* Instrument a member access. */
146 cp_ubsan_maybe_instrument_member_access
147 (tree stmt
, cp_ubsan_check_member_access_data
*ucmd
)
149 if (DECL_ARTIFICIAL (TREE_OPERAND (stmt
, 1)))
152 tree base
= TREE_OPERAND (stmt
, 0);
153 if (!cp_ubsan_instrument_vptr_p (TREE_TYPE (base
)))
156 cp_walk_tree (&base
, cp_ubsan_check_member_access_r
, ucmd
, ucmd
->pset
);
158 base
= cp_ubsan_instrument_vptr (EXPR_LOCATION (stmt
), base
,
159 TREE_TYPE (base
), false,
160 UBSAN_MEMBER_ACCESS
);
161 TREE_OPERAND (stmt
, 0)
162 = build_fold_indirect_ref_loc (EXPR_LOCATION (stmt
), base
);
166 /* Attempt to instrument member accesses inside of the function.
167 cp_ubsan_maybe_instrument_member_access should be called on COMPONENT_REFs
168 in the GENERIC IL, but only when the field is actually accessed, not
169 merely when it's address is taken. Therefore we track in is_addr field
170 whether in the current context we are processing address taken
171 handled components or not. E.g. for &x->y[w->z] we want to call
172 cp_ubsan_maybe_instrument_member_access on *w.z COMPONENT_REF, but
176 cp_ubsan_check_member_access_r (tree
*stmt_p
, int *walk_subtrees
, void *data
)
178 tree stmt
= *stmt_p
, t
;
179 cp_ubsan_check_member_access_data
*ucmd
180 = (cp_ubsan_check_member_access_data
*) data
;
181 switch (TREE_CODE (stmt
))
184 t
= TREE_OPERAND (stmt
, 0);
185 while ((TREE_CODE (t
) == MEM_REF
|| INDIRECT_REF_P (t
))
186 && TREE_CODE (TREE_OPERAND (t
, 0)) == ADDR_EXPR
)
187 t
= TREE_OPERAND (TREE_OPERAND (t
, 0), 0);
188 if (handled_component_p (t
))
191 ucmd
->is_addr
= true;
192 cp_walk_tree (&t
, cp_ubsan_check_member_access_r
,
194 ucmd
->is_addr
= false;
199 t
= TREE_OPERAND (stmt
, 0);
200 if (TREE_CODE (t
) == ADDR_EXPR
)
203 t
= TREE_OPERAND (stmt
, 0);
204 cp_walk_tree (&t
, cp_ubsan_check_member_access_r
, data
, ucmd
->pset
);
208 if (!ucmd
->is_addr
&& cp_ubsan_maybe_instrument_member_access (stmt
, ucmd
))
215 if (ucmd
->is_addr
&& handled_component_p (stmt
))
217 int i
, len
= TREE_OPERAND_LENGTH (stmt
);
219 if (!handled_component_p (TREE_OPERAND (stmt
, 0)))
220 ucmd
->is_addr
= false;
221 for (i
= 0; i
< len
; i
++)
223 cp_walk_tree (&TREE_OPERAND (stmt
, i
),
224 cp_ubsan_check_member_access_r
, data
, ucmd
->pset
);
225 ucmd
->is_addr
= false;
227 ucmd
->is_addr
= true;
234 /* Instrument all member accesses inside GENERIC *T_P. */
237 cp_ubsan_instrument_member_accesses (tree
*t_p
)
239 if (cp_ubsan_instrument_vptr_p (NULL_TREE
))
242 cp_ubsan_check_member_access_data ucmd
;
244 ucmd
.is_addr
= false;
245 cp_walk_tree (t_p
, cp_ubsan_check_member_access_r
, &ucmd
, &pset
);
249 /* Instrument downcast. */
252 cp_ubsan_maybe_instrument_downcast (location_t loc
, tree type
,
253 tree intype
, tree op
)
255 if (!POINTER_TYPE_P (type
)
256 || !POINTER_TYPE_P (intype
)
257 || !POINTER_TYPE_P (TREE_TYPE (op
))
258 || !CLASS_TYPE_P (TREE_TYPE (TREE_TYPE (op
)))
259 || !is_properly_derived_from (TREE_TYPE (type
), TREE_TYPE (intype
)))
262 return cp_ubsan_maybe_instrument_vptr (loc
, op
, TREE_TYPE (type
), true,
263 TREE_CODE (type
) == POINTER_TYPE
264 ? UBSAN_DOWNCAST_POINTER
265 : UBSAN_DOWNCAST_REFERENCE
);
268 /* Instrument cast to virtual base. */
271 cp_ubsan_maybe_instrument_cast_to_vbase (location_t loc
, tree type
, tree op
)
273 return cp_ubsan_maybe_instrument_vptr (loc
, op
, type
, true,
274 UBSAN_CAST_TO_VBASE
);
277 /* Called from initialize_vtbl_ptrs via dfs_walk. BINFO is the base
278 which we want to initialize the vtable pointer for, DATA is
279 TREE_LIST whose TREE_VALUE is the this ptr expression. */
282 cp_ubsan_dfs_initialize_vtbl_ptrs (tree binfo
, void *data
)
284 if (!TYPE_CONTAINS_VPTR_P (BINFO_TYPE (binfo
)))
285 return dfs_skip_bases
;
287 if (!BINFO_PRIMARY_P (binfo
))
289 tree base_ptr
= TREE_VALUE ((tree
) data
);
291 base_ptr
= build_base_path (PLUS_EXPR
, base_ptr
, binfo
, /*nonnull=*/1,
292 tf_warning_or_error
);
294 /* Compute the location of the vtpr. */
296 = build_vfield_ref (cp_build_indirect_ref (base_ptr
, RO_NULL
,
297 tf_warning_or_error
),
299 gcc_assert (vtbl_ptr
!= error_mark_node
);
301 /* Assign NULL to the vptr. */
302 tree vtbl
= build_zero_cst (TREE_TYPE (vtbl_ptr
));
303 tree stmt
= cp_build_modify_expr (input_location
, vtbl_ptr
, NOP_EXPR
,
304 vtbl
, tf_warning_or_error
);
305 if (vptr_via_virtual_p (binfo
))
306 /* If this vptr comes from a virtual base of the complete object, only
307 clear it if we're in charge of virtual bases. */
308 stmt
= build_if_in_charge (stmt
);
309 finish_expr_stmt (stmt
);
315 /* Initialize all the vtable pointers in the object pointed to by
316 ADDR to NULL, so that we catch invalid calls to methods before
317 mem-initializers are completed. */
320 cp_ubsan_maybe_initialize_vtbl_ptrs (tree addr
)
322 if (!cp_ubsan_instrument_vptr_p (NULL_TREE
))
325 tree type
= TREE_TYPE (TREE_TYPE (addr
));
326 tree list
= build_tree_list (type
, addr
);
327 /* We cannot rely on the vtable being set up. We have to indirect via the
329 int save_in_base_initializer
= in_base_initializer
;
330 in_base_initializer
= 1;
332 /* Walk through the hierarchy, initializing the vptr in each base
334 dfs_walk_once (TYPE_BINFO (type
), cp_ubsan_dfs_initialize_vtbl_ptrs
,
337 in_base_initializer
= save_in_base_initializer
;