On Fri, 27 Jun 2014, Jakub Jelinek wrote:
> Hi!
>
> This patch implements sanitization for nonnull and returns_nonnull
> attributes.
> Similarly to -fsanitize=null this option disables
> -fdelete-null-pointer-checks silently, and adds checks before calling
> functions with declared nonnull arguments if we don't pass NULL there,
> and before return in functions declared with returns_nonnull also inserts
> check whether the return value is not NULL.
>
> As GCC 4.9.0+ now aggressively optimizes based on these attributes and we've
> seen several issues in real world apps, I think this is really needed.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux normally (yes,rtl
> checking) and c,c++,fortran release checking bootstrap-ubsan.
>
> Will post bugs in gcc discovered by it later.
>
> The patch adds two new (trivial handlers) to libubsan, as it is maintained
> in llvm's compiler-rt, will talk to them if they are interested in those
> and what exact wording and form (AFAIK clang also added the gcc
> {,returns_}nonnull attributes). If they wouldn't be interested, guess
> we could add them in a separate, gcc owned, source file in ubsan (like we
> own Makefile*).
Looks good to me.
Thanks for adding this!
Richard.
> 2014-06-27 Jakub Jelinek <ja...@redhat.com>
>
> * flag-types.h (enum sanitize_code): Add SANITIZE_NONNULL and
> SANITIZE_RETURNS_NONNULL, or them into SANITIZE_UNDEFINED.
> * opts.c (common_handle_option): Handle SANITIZE_NONNULL and
> SANITIZE_RETURNS_NONNULL and disable flag_delete_null_pointer_checks
> for them.
> * sanitizer.def (BUILT_IN_UBSAN_HANDLE_NONNULL_ARG,
> BUILT_IN_UBSAN_HANDLE_NONNULL_ARG_ABORT,
> BUILT_IN_UBSAN_HANDLE_NONNULL_RETURN,
> BUILT_IN_UBSAN_HANDLE_NONNULL_RETURN_ABORT): New.
> * ubsan.c (instrument_bool_enum_load): Set *gsi back to
> stmt's iterator.
> (instrument_nonnull_arg, instrument_nonnull_return): New functions.
> (pass_ubsan::gate): Return true even for SANITIZE_NONNULL
> or SANITIZE_RETURNS_NONNULL.
> (pass_ubsan::execute): Call instrument_nonnull_{arg,return}.
>
> * c-c++-common/ubsan/nonnull-1.c: New test.
> * c-c++-common/ubsan/nonnull-2.c: New test.
> * c-c++-common/ubsan/nonnull-3.c: New test.
> * c-c++-common/ubsan/nonnull-4.c: New test.
> * c-c++-common/ubsan/nonnull-5.c: New test.
>
> --- gcc/flag-types.h.jj 2014-06-20 23:26:24.000000000 +0200
> +++ gcc/flag-types.h 2014-06-26 14:39:44.133970103 +0200
> @@ -231,10 +231,13 @@ enum sanitize_code {
> SANITIZE_FLOAT_DIVIDE = 1 << 12,
> SANITIZE_FLOAT_CAST = 1 << 13,
> SANITIZE_BOUNDS = 1 << 14,
> + SANITIZE_NONNULL = 1 << 15,
> + SANITIZE_RETURNS_NONNULL = 1 << 16,
> SANITIZE_UNDEFINED = SANITIZE_SHIFT | SANITIZE_DIVIDE |
> SANITIZE_UNREACHABLE
> | SANITIZE_VLA | SANITIZE_NULL | SANITIZE_RETURN
> | SANITIZE_SI_OVERFLOW | SANITIZE_BOOL | SANITIZE_ENUM
> - | SANITIZE_BOUNDS,
> + | SANITIZE_BOUNDS | SANITIZE_NONNULL
> + | SANITIZE_RETURNS_NONNULL,
> SANITIZE_NONDEFAULT = SANITIZE_FLOAT_DIVIDE | SANITIZE_FLOAT_CAST
> };
>
> --- gcc/opts.c.jj 2014-06-20 23:26:23.000000000 +0200
> +++ gcc/opts.c 2014-06-26 14:43:51.620652007 +0200
> @@ -1468,6 +1468,9 @@ common_handle_option (struct gcc_options
> { "float-cast-overflow", SANITIZE_FLOAT_CAST,
> sizeof "float-cast-overflow" - 1 },
> { "bounds", SANITIZE_BOUNDS, sizeof "bounds" - 1 },
> + { "nonnull", SANITIZE_NONNULL, sizeof "nonnull" - 1 },
> + { "returns-nonnull", SANITIZE_RETURNS_NONNULL,
> + sizeof "returns-nonnull" - 1 },
> { NULL, 0, 0 }
> };
> const char *comma;
> @@ -1511,7 +1514,8 @@ common_handle_option (struct gcc_options
>
> /* When instrumenting the pointers, we don't want to remove
> the null pointer checks. */
> - if (flag_sanitize & SANITIZE_NULL)
> + if (flag_sanitize & (SANITIZE_NULL | SANITIZE_NONNULL
> + | SANITIZE_RETURNS_NONNULL))
> opts->x_flag_delete_null_pointer_checks = 0;
> break;
> }
> --- gcc/sanitizer.def.jj 2014-06-20 23:26:23.000000000 +0200
> +++ gcc/sanitizer.def 2014-06-26 16:52:34.644801331 +0200
> @@ -417,3 +417,19 @@ DEF_SANITIZER_BUILTIN(BUILT_IN_UBSAN_HAN
> "__ubsan_handle_out_of_bounds_abort",
> BT_FN_VOID_PTR_PTR,
> ATTR_COLD_NORETURN_NOTHROW_LEAF_LIST)
> +DEF_SANITIZER_BUILTIN(BUILT_IN_UBSAN_HANDLE_NONNULL_ARG,
> + "__ubsan_handle_nonnull_arg",
> + BT_FN_VOID_PTR_PTRMODE,
> + ATTR_COLD_NOTHROW_LEAF_LIST)
> +DEF_SANITIZER_BUILTIN(BUILT_IN_UBSAN_HANDLE_NONNULL_ARG_ABORT,
> + "__ubsan_handle_nonnull_arg_abort",
> + BT_FN_VOID_PTR_PTRMODE,
> + ATTR_COLD_NORETURN_NOTHROW_LEAF_LIST)
> +DEF_SANITIZER_BUILTIN(BUILT_IN_UBSAN_HANDLE_NONNULL_RETURN,
> + "__ubsan_handle_nonnull_return",
> + BT_FN_VOID_PTR,
> + ATTR_COLD_NOTHROW_LEAF_LIST)
> +DEF_SANITIZER_BUILTIN(BUILT_IN_UBSAN_HANDLE_NONNULL_RETURN_ABORT,
> + "__ubsan_handle_nonnull_return_abort",
> + BT_FN_VOID_PTR,
> + ATTR_COLD_NORETURN_NOTHROW_LEAF_LIST)
> --- gcc/ubsan.c.jj 2014-06-20 23:26:24.000000000 +0200
> +++ gcc/ubsan.c 2014-06-26 18:23:28.190191706 +0200
> @@ -997,6 +997,7 @@ instrument_bool_enum_load (gimple_stmt_i
> }
> gimple_set_location (g, loc);
> gsi_insert_before (&gsi2, g, GSI_SAME_STMT);
> + *gsi = gsi_for_stmt (stmt);
> }
>
> /* Instrument float point-to-integer conversion. TYPE is an integer type of
> @@ -1121,6 +1122,117 @@ ubsan_instrument_float_cast (location_t
> fn, integer_zero_node);
> }
>
> +/* Instrument values passed to function arguments with nonnull attribute. */
> +
> +static void
> +instrument_nonnull_arg (gimple_stmt_iterator *gsi)
> +{
> + gimple stmt = gsi_stmt (*gsi);
> + location_t loc = gimple_location (stmt);
> + /* infer_nonnull_range needs flag_delete_null_pointer_checks set,
> + while for nonnull sanitization it is clear. */
> + int save_flag_delete_null_pointer_checks = flag_delete_null_pointer_checks;
> + flag_delete_null_pointer_checks = 1;
> + for (unsigned int i = 0; i < gimple_call_num_args (stmt); i++)
> + {
> + tree arg = gimple_call_arg (stmt, i);
> + if (POINTER_TYPE_P (TREE_TYPE (arg))
> + && infer_nonnull_range (stmt, arg, false, true))
> + {
> + gimple g;
> + if (!is_gimple_val (arg))
> + {
> + g = gimple_build_assign (make_ssa_name (TREE_TYPE (arg), NULL),
> + arg);
> + gimple_set_location (g, loc);
> + gsi_insert_before (gsi, g, GSI_SAME_STMT);
> + arg = gimple_assign_lhs (g);
> + }
> +
> + basic_block then_bb, fallthru_bb;
> + *gsi = create_cond_insert_point (gsi, true, false, true,
> + &then_bb, &fallthru_bb);
> + g = gimple_build_cond (EQ_EXPR, arg,
> + build_zero_cst (TREE_TYPE (arg)),
> + NULL_TREE, NULL_TREE);
> + gimple_set_location (g, loc);
> + gsi_insert_after (gsi, g, GSI_NEW_STMT);
> +
> + *gsi = gsi_after_labels (then_bb);
> + if (flag_sanitize_undefined_trap_on_error)
> + g = gimple_build_call (builtin_decl_explicit (BUILT_IN_TRAP), 0);
> + else
> + {
> + tree data = ubsan_create_data ("__ubsan_nonnull_arg_data",
> + &loc, NULL, NULL_TREE);
> + data = build_fold_addr_expr_loc (loc, data);
> + enum built_in_function bcode
> + = flag_sanitize_recover
> + ? BUILT_IN_UBSAN_HANDLE_NONNULL_ARG
> + : BUILT_IN_UBSAN_HANDLE_NONNULL_ARG_ABORT;
> + tree fn = builtin_decl_explicit (bcode);
> +
> + g = gimple_build_call (fn, 2, data,
> + build_int_cst (pointer_sized_int_node,
> + i + 1));
> + }
> + gimple_set_location (g, loc);
> + gsi_insert_before (gsi, g, GSI_SAME_STMT);
> + }
> + *gsi = gsi_for_stmt (stmt);
> + }
> + flag_delete_null_pointer_checks = save_flag_delete_null_pointer_checks;
> +}
> +
> +/* Instrument returns in functions with returns_nonnull attribute. */
> +
> +static void
> +instrument_nonnull_return (gimple_stmt_iterator *gsi)
> +{
> + gimple stmt = gsi_stmt (*gsi);
> + location_t loc = gimple_location (stmt);
> + tree arg = gimple_return_retval (stmt);
> + /* infer_nonnull_range needs flag_delete_null_pointer_checks set,
> + while for nonnull return sanitization it is clear. */
> + int save_flag_delete_null_pointer_checks = flag_delete_null_pointer_checks;
> + flag_delete_null_pointer_checks = 1;
> + if (arg
> + && POINTER_TYPE_P (TREE_TYPE (arg))
> + && is_gimple_val (arg)
> + && infer_nonnull_range (stmt, arg, false, true))
> + {
> + basic_block then_bb, fallthru_bb;
> + *gsi = create_cond_insert_point (gsi, true, false, true,
> + &then_bb, &fallthru_bb);
> + gimple g = gimple_build_cond (EQ_EXPR, arg,
> + build_zero_cst (TREE_TYPE (arg)),
> + NULL_TREE, NULL_TREE);
> + gimple_set_location (g, loc);
> + gsi_insert_after (gsi, g, GSI_NEW_STMT);
> +
> + *gsi = gsi_after_labels (then_bb);
> + if (flag_sanitize_undefined_trap_on_error)
> + g = gimple_build_call (builtin_decl_explicit (BUILT_IN_TRAP), 0);
> + else
> + {
> + tree data = ubsan_create_data ("__ubsan_nonnull_return_data",
> + &loc, NULL, NULL_TREE);
> + data = build_fold_addr_expr_loc (loc, data);
> + enum built_in_function bcode
> + = flag_sanitize_recover
> + ? BUILT_IN_UBSAN_HANDLE_NONNULL_RETURN
> + : BUILT_IN_UBSAN_HANDLE_NONNULL_RETURN_ABORT;
> + tree fn = builtin_decl_explicit (bcode);
> +
> + g = gimple_build_call (fn, 1, data);
> + }
> + gimple_set_location (g, loc);
> + gsi_insert_before (gsi, g, GSI_SAME_STMT);
> + *gsi = gsi_for_stmt (stmt);
> + }
> + flag_delete_null_pointer_checks = save_flag_delete_null_pointer_checks;
> +}
> +
> namespace {
>
> const pass_data pass_data_ubsan =
> @@ -1148,7 +1260,8 @@ public:
> virtual bool gate (function *)
> {
> return flag_sanitize & (SANITIZE_NULL | SANITIZE_SI_OVERFLOW
> - | SANITIZE_BOOL | SANITIZE_ENUM);
> + | SANITIZE_BOOL | SANITIZE_ENUM
> + | SANITIZE_NONNULL | SANITIZE_RETURNS_NONNULL);
> }
>
> virtual unsigned int execute (function *);
> @@ -1188,7 +1301,25 @@ pass_ubsan::execute (function *fun)
>
> if (flag_sanitize & (SANITIZE_BOOL | SANITIZE_ENUM)
> && gimple_assign_load_p (stmt))
> - instrument_bool_enum_load (&gsi);
> + {
> + instrument_bool_enum_load (&gsi);
> + bb = gimple_bb (stmt);
> + }
> +
> + if ((flag_sanitize & SANITIZE_NONNULL)
> + && is_gimple_call (stmt)
> + && !gimple_call_internal_p (stmt))
> + {
> + instrument_nonnull_arg (&gsi);
> + bb = gimple_bb (stmt);
> + }
> +
> + if ((flag_sanitize & SANITIZE_RETURNS_NONNULL)
> + && gimple_code (stmt) == GIMPLE_RETURN)
> + {
> + instrument_nonnull_return (&gsi);
> + bb = gimple_bb (stmt);
> + }
>
> gsi_next (&gsi);
> }
> --- gcc/testsuite/c-c++-common/ubsan/nonnull-1.c.jj 2014-06-26
> 18:19:27.655457620 +0200
> +++ gcc/testsuite/c-c++-common/ubsan/nonnull-1.c 2014-06-26
> 18:27:22.038955861 +0200
> @@ -0,0 +1,38 @@
> +/* { dg-do run } */
> +/* { dg-options "-fsanitize=nonnull,returns-nonnull" } */
> +
> +int q, r;
> +void *a, *b, *c = (void *) &q, *d, *e, *f = (void *) &q, *g, *h;
> +
> +__attribute__((returns_nonnull, nonnull (1, 3)))
> +void *
> +foo (void *p, void *q, void *r)
> +{
> + a = p;
> + b = r;
> + return q;
> +}
> +
> +int
> +bar (const void *a, const void *b)
> +{
> + int c = *(const int *) a;
> + int d = *(const int *) b;
> + return c - d;
> +}
> +
> +int
> +main ()
> +{
> + asm volatile ("" : : : "memory");
> + d = foo (c, b, c);
> + e = foo (e, c, f);
> + g = foo (c, f, g);
> + __builtin_memset (d, '\0', q);
> + return 0;
> +}
> +
> +/* { dg-output "\.c:13:\[0-9]*:\[^\n\r]*null return value where non-null
> required\[^\n\r]*(\n|\r\n|\r)" } */
> +/* { dg-output "\[^\n\r]*\.c:29:\[0-9]*:\[^\n\r]*null argument where
> non-null required .argument 1.\[^\n\r]*(\n|\r\n|\r)" } */
> +/* { dg-output "\[^\n\r]*\.c:30:\[0-9]*:\[^\n\r]*null argument where
> non-null required .argument 3.\[^\n\r]*(\n|\r\n|\r)" } */
> +/* { dg-output "\[^\n\r]*\.c:31:\[0-9]*:\[^\n\r]*null argument where
> non-null required .argument 1." } */
> --- gcc/testsuite/c-c++-common/ubsan/nonnull-2.c.jj 2014-06-26
> 18:28:36.151565589 +0200
> +++ gcc/testsuite/c-c++-common/ubsan/nonnull-2.c 2014-06-26
> 18:29:36.392248392 +0200
> @@ -0,0 +1,36 @@
> +/* { dg-do run } */
> +/* { dg-shouldfail "ubsan" } */
> +/* { dg-options "-fsanitize=undefined -fno-sanitize-recover" } */
> +
> +int q, r;
> +void *a, *b, *c = (void *) &q, *d, *e, *f = (void *) &q, *g, *h;
> +
> +__attribute__((returns_nonnull, nonnull (1, 3)))
> +void *
> +foo (void *p, void *q, void *r)
> +{
> + a = p;
> + b = r;
> + return q;
> +}
> +
> +int
> +bar (const void *a, const void *b)
> +{
> + int c = *(const int *) a;
> + int d = *(const int *) b;
> + return c - d;
> +}
> +
> +int
> +main ()
> +{
> + asm volatile ("" : : : "memory");
> + d = foo (c, b, c);
> + e = foo (e, c, f);
> + g = foo (c, f, g);
> + __builtin_memset (d, '\0', q);
> + return 0;
> +}
> +
> +/* { dg-output "\.c:14:\[0-9]*:\[^\n\r]*null return value where non-null
> required" } */
> --- gcc/testsuite/c-c++-common/ubsan/nonnull-3.c.jj 2014-06-26
> 18:29:50.883172086 +0200
> +++ gcc/testsuite/c-c++-common/ubsan/nonnull-3.c 2014-06-26
> 18:31:39.152601753 +0200
> @@ -0,0 +1,36 @@
> +/* { dg-do run } */
> +/* { dg-shouldfail "ubsan" } */
> +/* { dg-options "-fsanitize=undefined -fno-sanitize-recover" } */
> +
> +int q, r;
> +void *a, *b, *c = (void *) &q, *d, *e, *f = (void *) &q, *g, *h;
> +
> +__attribute__((returns_nonnull, nonnull (1, 3)))
> +void *
> +foo (void *p, void *q, void *r)
> +{
> + a = p;
> + b = r;
> + return q;
> +}
> +
> +int
> +bar (const void *a, const void *b)
> +{
> + int c = *(const int *) a;
> + int d = *(const int *) b;
> + return c - d;
> +}
> +
> +int
> +main ()
> +{
> + asm volatile ("" : : : "memory");
> + d = foo (c, (void *) &r, c);
> + e = foo (e, c, f);
> + g = foo (c, f, g);
> + __builtin_memset (d, '\0', q);
> + return 0;
> +}
> +
> +/* { dg-output "\.c:30:\[0-9]*:\[^\n\r]*null argument where non-null
> required .argument 1." } */
> --- gcc/testsuite/c-c++-common/ubsan/nonnull-4.c.jj 2014-06-26
> 18:31:49.118552359 +0200
> +++ gcc/testsuite/c-c++-common/ubsan/nonnull-4.c 2014-06-26
> 18:32:13.526423944 +0200
> @@ -0,0 +1,34 @@
> +/* { dg-do run } */
> +/* { dg-shouldfail "ubsan" } */
> +/* { dg-options "-fsanitize=undefined -fsanitize-undefined-trap-on-error" }
> */
> +
> +int q, r;
> +void *a, *b, *c = (void *) &q, *d, *e, *f = (void *) &q, *g, *h;
> +
> +__attribute__((returns_nonnull, nonnull (1, 3)))
> +void *
> +foo (void *p, void *q, void *r)
> +{
> + a = p;
> + b = r;
> + return q;
> +}
> +
> +int
> +bar (const void *a, const void *b)
> +{
> + int c = *(const int *) a;
> + int d = *(const int *) b;
> + return c - d;
> +}
> +
> +int
> +main ()
> +{
> + asm volatile ("" : : : "memory");
> + d = foo (c, b, c);
> + e = foo (e, c, f);
> + g = foo (c, f, g);
> + __builtin_memset (d, '\0', q);
> + return 0;
> +}
> --- gcc/testsuite/c-c++-common/ubsan/nonnull-5.c.jj 2014-06-26
> 18:32:23.284367076 +0200
> +++ gcc/testsuite/c-c++-common/ubsan/nonnull-5.c 2014-06-26
> 18:33:42.154968619 +0200
> @@ -0,0 +1,34 @@
> +/* { dg-do run } */
> +/* { dg-shouldfail "ubsan" } */
> +/* { dg-options "-fsanitize=undefined -fsanitize-undefined-trap-on-error" }
> */
> +
> +int q, r;
> +void *a, *b, *c = (void *) &q, *d, *e, *f = (void *) &q, *g, *h;
> +
> +__attribute__((returns_nonnull, nonnull (1, 3)))
> +void *
> +foo (void *p, void *q, void *r)
> +{
> + a = p;
> + b = r;
> + return q;
> +}
> +
> +int
> +bar (const void *a, const void *b)
> +{
> + int c = *(const int *) a;
> + int d = *(const int *) b;
> + return c - d;
> +}
> +
> +int
> +main ()
> +{
> + asm volatile ("" : : : "memory");
> + d = foo (c, (void *) &r, c);
> + e = foo (e, c, f);
> + g = foo (c, f, g);
> + __builtin_memset (d, '\0', q);
> + return 0;
> +}
> --- libsanitizer/ubsan/ubsan_handlers.cc.jj 2013-12-05 12:04:32.000000000
> +0100
> +++ libsanitizer/ubsan/ubsan_handlers.cc 2014-06-26 17:03:48.018251367
> +0200
> @@ -277,3 +277,31 @@ void __ubsan::__ubsan_handle_function_ty
> __ubsan_handle_function_type_mismatch(Data, Function);
> Die();
> }
> +
> +void __ubsan::__ubsan_handle_nonnull_arg(NonNullArgData *Data, uptr ArgNo) {
> + SourceLocation Loc = Data->Loc.acquire();
> + if (Loc.isDisabled())
> + return;
> +
> + Diag(Loc, DL_Error, "null argument where non-null required "
> + "(argument %0)") << ArgNo;
> +}
> +
> +void __ubsan::__ubsan_handle_nonnull_arg_abort(NonNullArgData *Data,
> + uptr ArgNo) {
> + __ubsan::__ubsan_handle_nonnull_arg(Data, ArgNo);
> + Die();
> +}
> +
> +void __ubsan::__ubsan_handle_nonnull_return(NonNullRetData *Data) {
> + SourceLocation Loc = Data->Loc.acquire();
> + if (Loc.isDisabled())
> + return;
> +
> + Diag(Loc, DL_Error, "null return value where non-null required");
> +}
> +
> +void __ubsan::__ubsan_handle_nonnull_return_abort(NonNullRetData *Data) {
> + __ubsan::__ubsan_handle_nonnull_return(Data);
> + Die();
> +}
> --- libsanitizer/ubsan/ubsan_handlers.h.jj 2013-12-05 12:04:32.000000000
> +0100
> +++ libsanitizer/ubsan/ubsan_handlers.h 2014-06-26 17:02:03.330803480
> +0200
> @@ -119,6 +119,20 @@ RECOVERABLE(function_type_mismatch,
> FunctionTypeMismatchData *Data,
> ValueHandle Val)
>
> +struct NonNullArgData {
> + SourceLocation Loc;
> +};
> +
> +/// \brief Handle passing null to function argument with nonnull attribute.
> +RECOVERABLE(nonnull_arg, NonNullArgData *Data, uptr ArgNo)
> +
> +struct NonNullRetData {
> + SourceLocation Loc;
> +};
> +
> +/// \brief Handle returning null from function with returns_nonnull
> attribute.
> +RECOVERABLE(nonnull_return, NonNullRetData *Data)
> +
> }
>
> #endif // UBSAN_HANDLERS_H
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
GF: Jeff Hawn, Jennifer Guild, Felix Imend"orffer
