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Handle all UBSAN built-ins in -Wuninitialized [PR101300].

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Resolves:
PR middle-end/101300 - -fsanitize=undefined suppresses -Wuninitialized for a VLA read at -O0

gcc/ChangeLog:
	PR middle-end/101300
	* tree-ssa-uninit.c (check_defs): Handle UBSAN built-ins.

gcc/testsuite/ChangeLog:
	PR middle-end/101300
	* gcc.dg/uninit-pr101300.c: New test.
This commit is contained in:
Martin Sebor 2021-07-20 13:08:39 -06:00
parent 818203714e
commit e07d30fdca
2 changed files with 73 additions and 3 deletions
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53
gcc/testsuite/gcc.dg/uninit-pr101300.c Normal file
View file

@ -0,0 +1,53 @@
/* PR middle-end/101300 - -fsanitize=undefined suppresses -Wuninitialized
for a VLA read at -O0
{ dg-do compile }
{ dg-options "-O0 -Wall -fsanitize=undefined" } */
int warn_vla_rd0 (int n)
{
char a[n];
return a[0]; // { dg-warning "\\\[-Wuninitialized]" }
}
int warn_vla_rd1 (int n)
{
char a[n];
return a[1]; // { dg-warning "\\\[-Wuninitialized]" }
}
int warn_vla_rdi (int n, int i)
{
char a[n];
return a[i]; // { dg-warning "\\\[-Wuninitialized]" }
}
int warn_vla_wr0_rd2_1_0 (int n)
{
char a[n];
a[0] = __LINE__;
int x = a[2]; // { dg-warning "\\\[-Wuninitialized]" }
int y = a[1]; // { dg-warning "\\\[-Wuninitialized]" }
int z = a[0];
return x + y + z;
}
int warn_vla_wr1_rd2_1_0 (int n)
{
char a[n];
a[1] = __LINE__;
int x = a[2]; // { dg-warning "\\\[-Wuninitialized]" }
int y = a[1];
int z = a[0]; // { dg-warning "\\\[-Wuninitialized]" }
return x + y + z;
}
int warn_vla_wr2_rd2_1_0 (int n)
{
char a[n];
a[2] = __LINE__;
int x = a[2];
int y = a[1]; // { dg-warning "\\\[-Wuninitialized]" }
int z = a[0]; // { dg-warning "\\\[-Wuninitialized]" }
return x + y + z;
}

23
gcc/tree-ssa-uninit.c
View file

@ -228,9 +228,26 @@ check_defs (ao_ref *ref, tree vdef, void *data_)
gimple *def_stmt = SSA_NAME_DEF_STMT (vdef);
/* The ASAN_MARK intrinsic doesn't modify the variable. */
if (is_gimple_call (def_stmt)
&& gimple_call_internal_p (def_stmt, IFN_ASAN_MARK))
return false;
if (is_gimple_call (def_stmt))
{
if (gimple_call_internal_p (def_stmt)
&& gimple_call_internal_fn (def_stmt) == IFN_ASAN_MARK)
return false;
if (tree fndecl = gimple_call_fndecl (def_stmt))
{
/* Some sanitizer calls pass integer arguments to built-ins
that expect pointers. Avoid using gimple_call_builtin_p()
which fails for such calls. */
if (DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL)
{
built_in_function fncode = DECL_FUNCTION_CODE (fndecl);
if (fncode > BEGIN_SANITIZER_BUILTINS
&& fncode < END_SANITIZER_BUILTINS)
return false;
}
}
}
/* End of VLA scope is not a kill. */
if (gimple_call_builtin_p (def_stmt, BUILT_IN_STACK_RESTORE))