procyberian/gcc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

ubsan: -Wreturn-type and ubsan trap-on-error

Browse source 
I noticed that -fsanitize=undefined -fsanitize-undefined-trap-on-error was
omitting the usual -Wreturn-type warning for control flowing off the end of
a function.  This was because the warning code was looking for calls either
to __builtin_unreachable or the UBSan function, but these flags produce a
call to __builtin_trap instead.

gcc/c-family/ChangeLog:

	* c-ubsan.cc (ubsan_instrument_return): Use BUILTINS_LOCATION.

gcc/ChangeLog:

	* tree-cfg.cc (pass_warn_function_return::execute): Also check
	BUILT_IN_TRAP.

gcc/testsuite/ChangeLog:

	* g++.dg/ubsan/return-8.C: New test.
This commit is contained in:
Jason Merrill 2022-06-10 15:26:36 -04:00
parent 72b185189f
commit 2c11662391
3 changed files with 15 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
gcc/c-family/c-ubsan.cc
View file

@ -308,7 +308,9 @@ tree
ubsan_instrument_return (location_t loc)
{
if (flag_sanitize_undefined_trap_on_error)
return build_call_expr_loc (loc, builtin_decl_explicit (BUILT_IN_TRAP), 0);
return build_call_expr_loc
/* pass_warn_function_return checks for BUILTINS_LOCATION. */
(BUILTINS_LOCATION, builtin_decl_explicit (BUILT_IN_TRAP), 0);
tree data = ubsan_create_data ("__ubsan_missing_return_data", 1, &loc,
NULL_TREE, NULL_TREE);

9
gcc/testsuite/g++.dg/ubsan/return-8.C Normal file
View file

@ -0,0 +1,9 @@
// { dg-additional-options "-fsanitize=undefined -fsanitize-undefined-trap-on-error" }
bool b;
int f() {
if (b) return 42;
} // { dg-warning "-Wreturn-type" }
int main() { f(); }

5
gcc/tree-cfg.cc
View file

@ -9543,7 +9543,7 @@ pass_warn_function_return::execute (function *fun)
}
/* The C++ FE turns fallthrough from the end of non-void function
into __builtin_unreachable () call with BUILTINS_LOCATION.
Recognize those too. */
Recognize those as well as calls from ubsan_instrument_return. */
basic_block bb;
if (!warning_suppressed_p (fun->decl, OPT_Wreturn_type))
FOR_EACH_BB_FN (bb, fun)
@ -9555,7 +9555,8 @@ pass_warn_function_return::execute (function *fun)
if (last
&& ((LOCATION_LOCUS (gimple_location (last))
== BUILTINS_LOCATION
&& gimple_call_builtin_p (last, BUILT_IN_UNREACHABLE))
&& (gimple_call_builtin_p (last, BUILT_IN_UNREACHABLE)
|| gimple_call_builtin_p (last, BUILT_IN_TRAP)))
|| gimple_call_builtin_p (last, ubsan_missing_ret)))
{
gimple_stmt_iterator gsi = gsi_for_stmt (last);