Branch data Line data Source code
1 : : /* UndefinedBehaviorSanitizer, undefined behavior detector.
2 : : Copyright (C) 2014-2024 Free Software Foundation, Inc.
3 : : Contributed by Jakub Jelinek <jakub@redhat.com>
4 : :
5 : : This file is part of GCC.
6 : :
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
10 : : version.
11 : :
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
15 : : for more details.
16 : :
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/>. */
20 : :
21 : : #include "config.h"
22 : : #include "system.h"
23 : : #include "coretypes.h"
24 : : #include "cp-tree.h"
25 : : #include "ubsan.h"
26 : : #include "stringpool.h"
27 : : #include "attribs.h"
28 : : #include "asan.h"
29 : :
30 : : /* Test if we should instrument vptr access. */
31 : :
32 : : static bool
33 : 11772 : cp_ubsan_instrument_vptr_p (tree type)
34 : : {
35 : 11772 : if (!flag_rtti || (flag_sanitize_trap & SANITIZE_VPTR))
36 : : return false;
37 : :
38 : 11682 : if (!sanitize_flags_p (SANITIZE_VPTR))
39 : : return false;
40 : :
41 : 11682 : if (current_function_decl == NULL_TREE)
42 : : return false;
43 : :
44 : 11682 : if (type)
45 : : {
46 : 6527 : type = TYPE_MAIN_VARIANT (type);
47 : 6527 : if (!CLASS_TYPE_P (type) || !CLASSTYPE_VTABLES (type))
48 : : return false;
49 : : }
50 : :
51 : : return true;
52 : : }
53 : :
54 : : /* Helper function for
55 : : cp_ubsan_maybe_instrument_{member_{call,access},downcast}.
56 : : Instrument vptr access. */
57 : :
58 : : static tree
59 : 1320 : cp_ubsan_instrument_vptr (location_t loc, tree op, tree type, bool is_addr,
60 : : enum ubsan_null_ckind ckind)
61 : : {
62 : 1320 : type = TYPE_MAIN_VARIANT (type);
63 : 1320 : const char *mangled = mangle_type_string (type);
64 : 1320 : hashval_t str_hash1 = htab_hash_string (mangled);
65 : 1320 : hashval_t str_hash2 = iterative_hash (mangled, strlen (mangled), 0);
66 : 1320 : tree str_hash = wide_int_to_tree (uint64_type_node,
67 : 2640 : wi::uhwi (((uint64_t) str_hash1 << 32)
68 : 1320 : | str_hash2, 64));
69 : 1320 : if (!is_addr)
70 : 435 : op = build_fold_addr_expr_loc (loc, op);
71 : 1320 : op = save_expr (op);
72 : 2640 : tree vptr = fold_build3_loc (loc, COMPONENT_REF,
73 : 1320 : TREE_TYPE (TYPE_VFIELD (type)),
74 : : build_fold_indirect_ref_loc (loc, op),
75 : 1320 : TYPE_VFIELD (type), NULL_TREE);
76 : 1320 : vptr = fold_convert_loc (loc, pointer_sized_int_node, vptr);
77 : 1320 : vptr = fold_convert_loc (loc, uint64_type_node, vptr);
78 : 1320 : if (ckind == UBSAN_DOWNCAST_POINTER)
79 : : {
80 : 41 : tree cond = build2_loc (loc, NE_EXPR, boolean_type_node, op,
81 : 41 : build_zero_cst (TREE_TYPE (op)));
82 : : /* This is a compiler generated comparison, don't emit
83 : : e.g. -Wnonnull-compare warning for it. */
84 : 41 : suppress_warning (cond, OPT_Wnonnull_compare);
85 : 41 : vptr = build3_loc (loc, COND_EXPR, uint64_type_node, cond,
86 : 41 : vptr, build_int_cst (uint64_type_node, 0));
87 : : }
88 : 1320 : tree ti_decl = get_tinfo_decl (type);
89 : 1320 : mark_used (ti_decl);
90 : 1320 : tree ptype = build_pointer_type (type);
91 : 1320 : tree call
92 : 1320 : = build_call_expr_internal_loc (loc, IFN_UBSAN_VPTR,
93 : : void_type_node, 5, op, vptr, str_hash,
94 : : build_address (ti_decl),
95 : : build_int_cst (ptype, ckind));
96 : 1320 : TREE_SIDE_EFFECTS (call) = 1;
97 : 1320 : return fold_build2 (COMPOUND_EXPR, TREE_TYPE (op), call, op);
98 : : }
99 : :
100 : : /* Helper function for
101 : : cp_ubsan_maybe_instrument_{member_{call,access},downcast}.
102 : : Instrument vptr access if it should be instrumented, otherwise return
103 : : NULL_TREE. */
104 : :
105 : : static tree
106 : 4045 : cp_ubsan_maybe_instrument_vptr (location_t loc, tree op, tree type,
107 : : bool is_addr, enum ubsan_null_ckind ckind)
108 : : {
109 : 4045 : if (!cp_ubsan_instrument_vptr_p (type))
110 : : return NULL_TREE;
111 : 885 : return cp_ubsan_instrument_vptr (loc, op, type, is_addr, ckind);
112 : : }
113 : :
114 : : /* Instrument a member call (but not constructor call) if needed. */
115 : :
116 : : void
117 : 3963 : cp_ubsan_maybe_instrument_member_call (tree stmt)
118 : : {
119 : 3963 : if (call_expr_nargs (stmt) == 0)
120 : : return;
121 : 3963 : tree op, *opp;
122 : :
123 : 3963 : tree fn = CALL_EXPR_FN (stmt);
124 : 3963 : if (fn && TREE_CODE (fn) == OBJ_TYPE_REF)
125 : : {
126 : : /* Virtual function call: Sanitize the use of the object pointer in the
127 : : OBJ_TYPE_REF, since the vtable reference will SEGV otherwise (95221).
128 : : OBJ_TYPE_REF_EXPR is ptr->vptr[N] and OBJ_TYPE_REF_OBJECT is ptr. But
129 : : we can't be sure of finding OBJ_TYPE_REF_OBJECT in OBJ_TYPE_REF_EXPR
130 : : if the latter has been optimized, so we use a COMPOUND_EXPR below. */
131 : 113 : opp = &OBJ_TYPE_REF_EXPR (fn);
132 : 113 : op = OBJ_TYPE_REF_OBJECT (fn);
133 : : }
134 : : else
135 : : {
136 : : /* Non-virtual call: Sanitize the 'this' argument. */
137 : 3850 : opp = &CALL_EXPR_ARG (stmt, 0);
138 : 3850 : if (*opp == error_mark_node
139 : 3850 : || !INDIRECT_TYPE_P (TREE_TYPE (*opp)))
140 : : return;
141 : 6133 : while (TREE_CODE (*opp) == COMPOUND_EXPR)
142 : 2283 : opp = &TREE_OPERAND (*opp, 1);
143 : : op = *opp;
144 : : }
145 : 3963 : op = cp_ubsan_maybe_instrument_vptr (EXPR_LOCATION (stmt), op,
146 : 3963 : TREE_TYPE (TREE_TYPE (op)),
147 : : true, UBSAN_MEMBER_CALL);
148 : 3963 : if (!op)
149 : : /* No change. */;
150 : 805 : else if (fn && TREE_CODE (fn) == OBJ_TYPE_REF)
151 : 113 : *opp = cp_build_compound_expr (op, *opp, tf_none);
152 : : else
153 : 692 : *opp = op;
154 : : }
155 : :
156 : : /* Data passed to cp_ubsan_check_member_access_r. */
157 : :
158 : : struct cp_ubsan_check_member_access_data
159 : : {
160 : : hash_set<tree> *pset;
161 : : bool is_addr;
162 : : };
163 : :
164 : : static tree cp_ubsan_check_member_access_r (tree *, int *, void *);
165 : :
166 : : /* Instrument a member access. */
167 : :
168 : : static bool
169 : 5081 : cp_ubsan_maybe_instrument_member_access
170 : : (tree stmt, cp_ubsan_check_member_access_data *ucmd)
171 : : {
172 : 5081 : if (DECL_ARTIFICIAL (TREE_OPERAND (stmt, 1)))
173 : : return false;
174 : :
175 : 2482 : tree base = TREE_OPERAND (stmt, 0);
176 : 2482 : if (!cp_ubsan_instrument_vptr_p (TREE_TYPE (base)))
177 : : return false;
178 : :
179 : 435 : cp_walk_tree (&base, cp_ubsan_check_member_access_r, ucmd, ucmd->pset);
180 : :
181 : 435 : base = cp_ubsan_instrument_vptr (EXPR_LOCATION (stmt), base,
182 : 435 : TREE_TYPE (base), false,
183 : : UBSAN_MEMBER_ACCESS);
184 : 435 : TREE_OPERAND (stmt, 0)
185 : 435 : = build_fold_indirect_ref_loc (EXPR_LOCATION (stmt), base);
186 : 435 : return true;
187 : : }
188 : :
189 : : /* Attempt to instrument member accesses inside of the function.
190 : : cp_ubsan_maybe_instrument_member_access should be called on COMPONENT_REFs
191 : : in the GENERIC IL, but only when the field is actually accessed, not
192 : : merely when it's address is taken. Therefore we track in is_addr field
193 : : whether in the current context we are processing address taken
194 : : handled components or not. E.g. for &x->y[w->z] we want to call
195 : : cp_ubsan_maybe_instrument_member_access on *w.z COMPONENT_REF, but
196 : : not on *x.y. */
197 : :
198 : : static tree
199 : 176219 : cp_ubsan_check_member_access_r (tree *stmt_p, int *walk_subtrees, void *data)
200 : : {
201 : 176219 : tree stmt = *stmt_p, t;
202 : 176219 : cp_ubsan_check_member_access_data *ucmd
203 : : = (cp_ubsan_check_member_access_data *) data;
204 : 176219 : switch (TREE_CODE (stmt))
205 : : {
206 : 14303 : case ADDR_EXPR:
207 : 14303 : t = TREE_OPERAND (stmt, 0);
208 : 28606 : while ((TREE_CODE (t) == MEM_REF || INDIRECT_REF_P (t))
209 : 14303 : && TREE_CODE (TREE_OPERAND (t, 0)) == ADDR_EXPR)
210 : 0 : t = TREE_OPERAND (TREE_OPERAND (t, 0), 0);
211 : 14303 : if (handled_component_p (t))
212 : : {
213 : 1291 : *walk_subtrees = 0;
214 : 1291 : ucmd->is_addr = true;
215 : 1291 : cp_walk_tree (&t, cp_ubsan_check_member_access_r,
216 : : data, ucmd->pset);
217 : 1291 : ucmd->is_addr = false;
218 : : }
219 : : break;
220 : 5855 : case MEM_REF:
221 : 5855 : case INDIRECT_REF:
222 : 5855 : t = TREE_OPERAND (stmt, 0);
223 : 5855 : if (TREE_CODE (t) == ADDR_EXPR)
224 : : {
225 : 21 : *walk_subtrees = 0;
226 : 21 : t = TREE_OPERAND (t, 0);
227 : 21 : cp_walk_tree (&t, cp_ubsan_check_member_access_r, data, ucmd->pset);
228 : : }
229 : : break;
230 : 6859 : case COMPONENT_REF:
231 : 6859 : if (!ucmd->is_addr && cp_ubsan_maybe_instrument_member_access (stmt, ucmd))
232 : : {
233 : 435 : *walk_subtrees = 0;
234 : 435 : break;
235 : : }
236 : : /* FALLTHRU */
237 : 155626 : default:
238 : 155626 : if (ucmd->is_addr && handled_component_p (stmt))
239 : : {
240 : 1800 : int i, len = TREE_OPERAND_LENGTH (stmt);
241 : 1800 : *walk_subtrees = 0;
242 : 1800 : if (!handled_component_p (TREE_OPERAND (stmt, 0)))
243 : 1288 : ucmd->is_addr = false;
244 : 7222 : for (i = 0; i < len; i++)
245 : : {
246 : 5422 : cp_walk_tree (&TREE_OPERAND (stmt, i),
247 : : cp_ubsan_check_member_access_r, data, ucmd->pset);
248 : 5422 : ucmd->is_addr = false;
249 : : }
250 : 1800 : ucmd->is_addr = true;
251 : : }
252 : : break;
253 : : }
254 : 176219 : return NULL_TREE;
255 : : }
256 : :
257 : : /* Instrument all member accesses inside GENERIC *T_P. */
258 : :
259 : : void
260 : 4828 : cp_ubsan_instrument_member_accesses (tree *t_p)
261 : : {
262 : 4828 : if (cp_ubsan_instrument_vptr_p (NULL_TREE))
263 : : {
264 : 4738 : hash_set<tree> pset;
265 : 4738 : cp_ubsan_check_member_access_data ucmd;
266 : 4738 : ucmd.pset = &pset;
267 : 4738 : ucmd.is_addr = false;
268 : 4738 : cp_walk_tree (t_p, cp_ubsan_check_member_access_r, &ucmd, &pset);
269 : 4738 : }
270 : 4828 : }
271 : :
272 : : /* Instrument downcast. */
273 : :
274 : : tree
275 : 385 : cp_ubsan_maybe_instrument_downcast (location_t loc, tree type,
276 : : tree intype, tree op)
277 : : {
278 : 385 : if (!INDIRECT_TYPE_P (type)
279 : 385 : || !INDIRECT_TYPE_P (intype)
280 : 43 : || !INDIRECT_TYPE_P (TREE_TYPE (op))
281 : 43 : || !CLASS_TYPE_P (TREE_TYPE (TREE_TYPE (op)))
282 : 428 : || !is_properly_derived_from (TREE_TYPE (type), TREE_TYPE (intype)))
283 : 342 : return NULL_TREE;
284 : :
285 : 43 : return cp_ubsan_maybe_instrument_vptr (loc, op, TREE_TYPE (type), true,
286 : 43 : TYPE_PTR_P (type)
287 : : ? UBSAN_DOWNCAST_POINTER
288 : 43 : : UBSAN_DOWNCAST_REFERENCE);
289 : : }
290 : :
291 : : /* Instrument cast to virtual base. */
292 : :
293 : : tree
294 : 39 : cp_ubsan_maybe_instrument_cast_to_vbase (location_t loc, tree type, tree op)
295 : : {
296 : 39 : return cp_ubsan_maybe_instrument_vptr (loc, op, type, true,
297 : 39 : UBSAN_CAST_TO_VBASE);
298 : : }
299 : :
300 : : /* Called from initialize_vtbl_ptrs via dfs_walk. BINFO is the base
301 : : which we want to initialize the vtable pointer for, DATA is
302 : : TREE_LIST whose TREE_VALUE is the this ptr expression. */
303 : :
304 : : static tree
305 : 585 : cp_ubsan_dfs_initialize_vtbl_ptrs (tree binfo, void *data)
306 : : {
307 : 585 : if (!TYPE_CONTAINS_VPTR_P (BINFO_TYPE (binfo)))
308 : : return dfs_skip_bases;
309 : :
310 : 287 : if (!BINFO_PRIMARY_P (binfo))
311 : : {
312 : 147 : tree base_ptr = TREE_VALUE ((tree) data);
313 : :
314 : 147 : base_ptr = build_base_path (PLUS_EXPR, base_ptr, binfo, /*nonnull=*/1,
315 : : tf_warning_or_error);
316 : :
317 : : /* Compute the location of the vtpr. */
318 : 147 : tree vtbl_ptr
319 : 147 : = build_vfield_ref (cp_build_fold_indirect_ref (base_ptr),
320 : 147 : TREE_TYPE (binfo));
321 : 147 : gcc_assert (vtbl_ptr != error_mark_node);
322 : :
323 : : /* Assign NULL to the vptr. */
324 : 147 : tree vtbl = build_zero_cst (TREE_TYPE (vtbl_ptr));
325 : 147 : tree stmt = cp_build_modify_expr (input_location, vtbl_ptr, NOP_EXPR,
326 : : vtbl, tf_warning_or_error);
327 : 147 : if (vptr_via_virtual_p (binfo))
328 : : /* If this vptr comes from a virtual base of the complete object, only
329 : : clear it if we're in charge of virtual bases. */
330 : 12 : stmt = build_if_in_charge (stmt);
331 : 147 : finish_expr_stmt (stmt);
332 : : }
333 : :
334 : : return NULL_TREE;
335 : : }
336 : :
337 : : /* Initialize all the vtable pointers in the object pointed to by
338 : : ADDR to NULL, so that we catch invalid calls to methods before
339 : : mem-initializers are completed. */
340 : :
341 : : void
342 : 417 : cp_ubsan_maybe_initialize_vtbl_ptrs (tree addr)
343 : : {
344 : 417 : if (!cp_ubsan_instrument_vptr_p (NULL_TREE))
345 : : return;
346 : :
347 : 417 : tree type = TREE_TYPE (TREE_TYPE (addr));
348 : 417 : tree list = build_tree_list (type, addr);
349 : : /* We cannot rely on the vtable being set up. We have to indirect via the
350 : : vtt_parm. */
351 : 417 : int save_in_base_initializer = in_base_initializer;
352 : 417 : in_base_initializer = 1;
353 : :
354 : : /* Walk through the hierarchy, initializing the vptr in each base
355 : : class to NULL. */
356 : 417 : dfs_walk_once (TYPE_BINFO (type), cp_ubsan_dfs_initialize_vtbl_ptrs,
357 : : NULL, list);
358 : :
359 : 417 : in_base_initializer = save_in_base_initializer;
360 : : }
|
