From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4441 invoked by alias); 31 Oct 2013 18:29:07 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 4430 invoked by uid 89); 31 Oct 2013 18:29:07 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.7 required=5.0 tests=AWL,BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 31 Oct 2013 18:29:05 +0000 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r9VIT0O2014829 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Thu, 31 Oct 2013 14:29:01 -0400 Received: from redhat.com (ovpn-116-47.ams2.redhat.com [10.36.116.47]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id r9VISur9009421 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Thu, 31 Oct 2013 14:28:58 -0400 Date: Thu, 31 Oct 2013 19:07:00 -0000 From: Marek Polacek To: Jason Merrill Cc: GCC Patches , Jakub Jelinek , "Joseph S. Myers" Subject: Re: [PATCH][ubsan] Add VLA bound instrumentation Message-ID: <20131031182855.GI31396@redhat.com> References: <20130925124132.GJ12296@redhat.com> <52697B9D.9000502@redhat.com> <20131025165803.GF27400@redhat.com> <526AB5CC.60408@redhat.com> <20131025190356.GG27400@redhat.com> <526AC0C9.1050003@redhat.com> <20131030145253.GB31396@redhat.com> <52712C29.3010206@redhat.com> <20131030161504.GC31396@redhat.com> <5271AE06.9020004@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5271AE06.9020004@redhat.com> User-Agent: Mutt/1.5.20 (2009-06-14) X-SW-Source: 2013-10/txt/msg02724.txt.bz2 On Wed, Oct 30, 2013 at 09:10:30PM -0400, Jason Merrill wrote: > On 10/30/2013 12:15 PM, Marek Polacek wrote: > >On Wed, Oct 30, 2013 at 11:56:25AM -0400, Jason Merrill wrote: > >>Saving 'size' here doesn't help since it's already been used above. > >>Could you use itype instead of size here? > > > >I already experimented with that and I think I can't, since we call > >the finish_expr_stmt too soon, which results in: > > > > int x = 1; > > int a[0:(sizetype) SAVE_EXPR ]; > > > > <>; > > < > if (SAVE_EXPR <= 0) > > { > > __builtin___ubsan_handle_vla_bound_not_positive (&*.Lubsan_data0, (unsigned long) SAVE_EXPR ); > > } > > else > > { > > 0 > > }, (void) SAVE_EXPR ; >>>>>; > > ssizetype D.2143; > > < > (void) (D.2143 = (ssizetype) ++x + -1) >>>>>; > > Ah, looks like you're getting an unfortunate interaction with > stabilize_vla_size, which is replacing the contents of the SAVE_EXPR > with a reference to a variable that isn't initialized yet. Perhaps > we should move the stabilize_vla_size call into > compute_array_index_type, too. That works, thanks. So implemented as below in the patch. I was quite nervous about dropping the guards before stabilize_vla_size, but we can't really use them in compute_array_index_type, also I don't see any new regressions or bootstrap failures. (The C++1y check was adjusted accordingly to your recent patch, so we never throw on zero-length arrays.) Regtested, ran bootstrap-ubsan on x86_64-linux, ok for you now? 2013-10-31 Marek Polacek Implement -fsanitize=vla-bound. * opts.c (common_handle_option): Handle vla-bound. * sanitizer.def (BUILT_IN_UBSAN_HANDLE_VLA_BOUND_NOT_POSITIVE): Define. * flag-types.h (enum sanitize_code): Add SANITIZE_VLA. * asan.c (initialize_sanitizer_builtins): Build BT_FN_VOID_PTR_PTR. c-family/ * c-ubsan.c: Don't include hash-table.h. (ubsan_instrument_vla): New function. * c-ubsan.h: Declare it. cp/ * decl.c (cp_finish_decl): Move C++1y bounds checking... (compute_array_index_type): ...here. Add VLA instrumentation. Call stabilize_vla_size. (grokdeclarator): Don't call stabilize_vla_size here. c/ * c-decl.c (grokdeclarator): Add VLA instrumentation. testsuite/ * g++.dg/ubsan/cxx1y-vla.C: New test. * c-c++-common/ubsan/vla-3.c: New test. * c-c++-common/ubsan/vla-2.c: New test. * c-c++-common/ubsan/vla-4.c: New test. * c-c++-common/ubsan/vla-1.c: New test. --- gcc/opts.c.mp 2013-10-31 18:06:23.269355759 +0100 +++ gcc/opts.c 2013-10-31 18:06:47.325449575 +0100 @@ -1444,6 +1444,7 @@ common_handle_option (struct gcc_options { "undefined", SANITIZE_UNDEFINED, sizeof "undefined" - 1 }, { "unreachable", SANITIZE_UNREACHABLE, sizeof "unreachable" - 1 }, + { "vla-bound", SANITIZE_VLA, sizeof "vla-bound" - 1 }, { NULL, 0, 0 } }; const char *comma; --- gcc/c-family/c-ubsan.c.mp 2013-10-31 18:06:23.263355735 +0100 +++ gcc/c-family/c-ubsan.c 2013-10-31 18:06:47.295449445 +0100 @@ -25,7 +25,6 @@ along with GCC; see the file COPYING3. #include "alloc-pool.h" #include "cgraph.h" #include "gimple.h" -#include "hash-table.h" #include "output.h" #include "toplev.h" #include "ubsan.h" @@ -86,8 +85,7 @@ ubsan_instrument_division (location_t lo return t; } -/* Instrument left and right shifts. If not instrumenting, return - NULL_TREE. */ +/* Instrument left and right shifts. */ tree ubsan_instrument_shift (location_t loc, enum tree_code code, @@ -157,4 +155,23 @@ ubsan_instrument_shift (location_t loc, t = fold_build3 (COND_EXPR, void_type_node, t, tt, void_zero_node); return t; +} + +/* Instrument variable length array bound. */ + +tree +ubsan_instrument_vla (location_t loc, tree size) +{ + tree type = TREE_TYPE (size); + tree t, tt; + + t = fold_build2 (LE_EXPR, boolean_type_node, size, build_int_cst (type, 0)); + tree data = ubsan_create_data ("__ubsan_vla_data", + loc, ubsan_type_descriptor (type), NULL_TREE); + data = build_fold_addr_expr_loc (loc, data); + tt = builtin_decl_explicit (BUILT_IN_UBSAN_HANDLE_VLA_BOUND_NOT_POSITIVE); + tt = build_call_expr_loc (loc, tt, 2, data, ubsan_encode_value (size)); + t = fold_build3 (COND_EXPR, void_type_node, t, tt, void_zero_node); + + return t; } --- gcc/c-family/c-ubsan.h.mp 2013-10-31 18:06:23.264355739 +0100 +++ gcc/c-family/c-ubsan.h 2013-10-31 18:06:47.296449449 +0100 @@ -23,5 +23,6 @@ along with GCC; see the file COPYING3. extern tree ubsan_instrument_division (location_t, tree, tree); extern tree ubsan_instrument_shift (location_t, enum tree_code, tree, tree); +extern tree ubsan_instrument_vla (location_t, tree); #endif /* GCC_C_UBSAN_H */ --- gcc/sanitizer.def.mp 2013-10-31 18:06:23.270355763 +0100 +++ gcc/sanitizer.def 2013-10-31 18:06:47.327449583 +0100 @@ -297,3 +297,7 @@ DEF_SANITIZER_BUILTIN(BUILT_IN_UBSAN_HAN "__ubsan_handle_builtin_unreachable", BT_FN_VOID_PTR, ATTR_COLD_NORETURN_NOTHROW_LEAF_LIST) +DEF_SANITIZER_BUILTIN(BUILT_IN_UBSAN_HANDLE_VLA_BOUND_NOT_POSITIVE, + "__ubsan_handle_vla_bound_not_positive", + BT_FN_VOID_PTR_PTR, + ATTR_COLD_NOTHROW_LEAF_LIST) --- gcc/flag-types.h.mp 2013-10-31 18:06:23.268355755 +0100 +++ gcc/flag-types.h 2013-10-31 18:06:47.324449570 +0100 @@ -210,7 +210,9 @@ enum sanitize_code { SANITIZE_SHIFT = 1 << 2, SANITIZE_DIVIDE = 1 << 3, SANITIZE_UNREACHABLE = 1 << 4, + SANITIZE_VLA = 1 << 5, SANITIZE_UNDEFINED = SANITIZE_SHIFT | SANITIZE_DIVIDE | SANITIZE_UNREACHABLE + | SANITIZE_VLA }; /* flag_vtable_verify initialization levels. */ --- gcc/cp/decl.c.mp 2013-10-31 18:06:23.267355751 +0100 +++ gcc/cp/decl.c 2013-10-31 18:06:47.320449552 +0100 @@ -45,6 +45,7 @@ along with GCC; see the file COPYING3. #include "c-family/c-objc.h" #include "c-family/c-pragma.h" #include "c-family/c-target.h" +#include "c-family/c-ubsan.h" #include "diagnostic.h" #include "intl.h" #include "debug.h" @@ -6399,17 +6400,6 @@ cp_finish_decl (tree decl, tree init, bo && TYPE_FOR_JAVA (type) && MAYBE_CLASS_TYPE_P (type)) error ("non-static data member %qD has Java class type", decl); - if (cxx_dialect >= cxx1y && array_of_runtime_bound_p (type)) - { - /* If the VLA bound is larger than half the address space, or less - than zero, throw std::bad_array_length. */ - tree max = convert (ssizetype, TYPE_MAX_VALUE (TYPE_DOMAIN (type))); - tree comp = build2 (LT_EXPR, boolean_type_node, max, ssize_int (-1)); - comp = build3 (COND_EXPR, void_type_node, comp, - throw_bad_array_length (), void_zero_node); - finish_expr_stmt (comp); - } - /* Add this declaration to the statement-tree. This needs to happen after the call to check_initializer so that the DECL_EXPR for a reference temp is added before the DECL_EXPR for the reference itself. */ @@ -8379,6 +8369,11 @@ compute_array_index_type (tree name, tre { /* A variable sized array. */ itype = variable_size (itype); + + /* We need to stabilize side-effects in VLA sizes for regular array + declarations too, not just pointers to arrays. */ + stabilize_vla_size (itype); + if (TREE_CODE (itype) != SAVE_EXPR) { /* Look for SIZEOF_EXPRs in itype and fold them, otherwise @@ -8390,6 +8385,31 @@ compute_array_index_type (tree name, tre if (found) itype = variable_size (fold (newitype)); } + + if (cxx_dialect >= cxx1y) + { + /* If the VLA bound is larger than half the address space, + or less than zero, throw std::bad_array_length. */ + tree comp = build2 (LT_EXPR, boolean_type_node, itype, + ssize_int (-1)); + comp = build3 (COND_EXPR, void_type_node, comp, + throw_bad_array_length (), void_zero_node); + finish_expr_stmt (comp); + } + + if ((flag_sanitize & SANITIZE_VLA) + /* From C++1y onwards, we throw an exception on a negative + length size of an array; see above */ + && cxx_dialect < cxx1y) + { + /* We have to add 1 -- in the ubsan routine we generate + LE_EXPR rather than LT_EXPR. */ + tree t = fold_build2 (PLUS_EXPR, TREE_TYPE (itype), itype, + build_one_cst (TREE_TYPE (itype))); + t = fold_build2 (COMPOUND_EXPR, TREE_TYPE (t), + ubsan_instrument_vla (input_location, t), t); + finish_expr_stmt (t); + } } /* Make sure that there was no overflow when creating to a signed index type. (For example, on a 32-bit machine, an array with @@ -9886,14 +9906,6 @@ grokdeclarator (const cp_declarator *dec } } - /* We need to stabilize side-effects in VLA sizes for regular array - declarations too, not just pointers to arrays. */ - if (type != error_mark_node && !TYPE_NAME (type) - && (decl_context == NORMAL || decl_context == FIELD) - && at_function_scope_p () - && variably_modified_type_p (type, NULL_TREE)) - stabilize_vla_size (TYPE_SIZE (type)); - /* A `constexpr' specifier used in an object declaration declares the object as `const'. */ if (constexpr_p && innermost_code != cdk_function) --- gcc/c/c-decl.c.mp 2013-10-31 18:06:23.265355743 +0100 +++ gcc/c/c-decl.c 2013-10-31 18:06:47.308449500 +0100 @@ -45,6 +45,7 @@ along with GCC; see the file COPYING3. #include "c-family/c-common.h" #include "c-family/c-objc.h" #include "c-family/c-pragma.h" +#include "c-family/c-ubsan.h" #include "c-lang.h" #include "langhooks.h" #include "tree-iterator.h" @@ -5411,6 +5412,16 @@ grokdeclarator (const struct c_declarato with known value. */ this_size_varies = size_varies = true; warn_variable_length_array (name, size); + if (flag_sanitize & SANITIZE_VLA + && decl_context == NORMAL) + { + /* Evaluate the array size only once. */ + size = c_save_expr (size); + size = c_fully_fold (size, false, NULL); + size = fold_build2 (COMPOUND_EXPR, TREE_TYPE (size), + ubsan_instrument_vla (loc, size), + size); + } } if (integer_zerop (size) && !this_size_varies) --- gcc/testsuite/g++.dg/ubsan/cxx1y-vla.C.mp 2013-10-31 18:09:03.019981937 +0100 +++ gcc/testsuite/g++.dg/ubsan/cxx1y-vla.C 2013-10-31 18:08:42.117900326 +0100 @@ -0,0 +1,13 @@ +/* { dg-do run } */ +/* { dg-options "-fsanitize=vla-bound -w -std=c++1y" } */ +/* { dg-shouldfail "ubsan" } */ + +int +main (void) +{ + int y = -18; + int a[y]; + return 0; +} + +/* { dg-output "terminate called after throwing an instance" } */ --- gcc/testsuite/c-c++-common/ubsan/vla-3.c.mp 2013-10-31 18:08:49.639929788 +0100 +++ gcc/testsuite/c-c++-common/ubsan/vla-3.c 2013-10-31 18:08:42.117900326 +0100 @@ -0,0 +1,16 @@ +/* { dg-do run } */ +/* { dg-options "-fsanitize=vla-bound -w" } */ + +/* Don't instrument the arrays here. */ +int +foo (int n, int a[]) +{ + return a[n - 1]; +} + +int +main (void) +{ + int a[6] = { }; + return foo (3, a); +} --- gcc/testsuite/c-c++-common/ubsan/vla-2.c.mp 2013-10-31 18:08:53.347944329 +0100 +++ gcc/testsuite/c-c++-common/ubsan/vla-2.c 2013-10-31 18:08:42.118900330 +0100 @@ -0,0 +1,15 @@ +/* { dg-do run } */ +/* { dg-options "-fsanitize=vla-bound -w" } */ + +int +main (void) +{ + const int t = 0; + struct s { + int x; + /* Don't instrument this one. */ + int g[t]; + }; + + return 0; +} --- gcc/testsuite/c-c++-common/ubsan/vla-4.c.mp 2013-10-31 18:08:56.852958019 +0100 +++ gcc/testsuite/c-c++-common/ubsan/vla-4.c 2013-10-31 18:08:42.119900334 +0100 @@ -0,0 +1,13 @@ +/* { dg-do run } */ +/* { dg-options "-fsanitize=vla-bound" } */ + +int +main (void) +{ + int x = 1; + /* Check that the size of an array is evaluated only once. */ + int a[++x]; + if (x != 2) + __builtin_abort (); + return 0; +} --- gcc/testsuite/c-c++-common/ubsan/vla-1.c.mp 2013-10-31 18:08:51.771938127 +0100 +++ gcc/testsuite/c-c++-common/ubsan/vla-1.c 2013-10-31 18:08:42.119900334 +0100 @@ -0,0 +1,48 @@ +/* { dg-do run } */ +/* { dg-options "-fsanitize=vla-bound -w" } */ + +static int +bar (void) +{ + return -42; +} + +typedef long int V; +int +main (void) +{ + int x = -1; + double di = -3.2; + V v = -666; + + int a[x]; + int aa[x][x]; + int aaa[x][x][x]; + int b[x - 4]; + int c[(int) di]; + int d[1 + x]; + int e[1 ? x : -1]; + int f[++x]; + int g[(signed char) --x]; + int h[(++x, --x, x)]; + int i[v]; + int j[bar ()]; + + return 0; +} + +/* { dg-output "variable length array bound evaluates to non-positive value -1(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*variable length array bound evaluates to non-positive value -1(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*variable length array bound evaluates to non-positive value -1(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*variable length array bound evaluates to non-positive value -1(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*variable length array bound evaluates to non-positive value -1(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*variable length array bound evaluates to non-positive value -1(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*variable length array bound evaluates to non-positive value -5(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*variable length array bound evaluates to non-positive value -3(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*variable length array bound evaluates to non-positive value 0(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*variable length array bound evaluates to non-positive value -1(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*variable length array bound evaluates to non-positive value 0(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*variable length array bound evaluates to non-positive value -1(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*variable length array bound evaluates to non-positive value -1(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*variable length array bound evaluates to non-positive value -666(\n|\r\n|\r)" } */ +/* { dg-output "\[^\n\r]*variable length array bound evaluates to non-positive value -42(\n|\r\n|\r)" } */ --- gcc/asan.c.mp 2013-10-31 18:06:02.861276291 +0100 +++ gcc/asan.c 2013-10-31 18:06:47.293449437 +0100 @@ -2021,6 +2021,9 @@ initialize_sanitizer_builtins (void) tree BT_FN_VOID = build_function_type_list (void_type_node, NULL_TREE); tree BT_FN_VOID_PTR = build_function_type_list (void_type_node, ptr_type_node, NULL_TREE); + tree BT_FN_VOID_PTR_PTR + = build_function_type_list (void_type_node, ptr_type_node, + ptr_type_node, NULL_TREE); tree BT_FN_VOID_PTR_PTR_PTR = build_function_type_list (void_type_node, ptr_type_node, ptr_type_node, ptr_type_node, NULL_TREE); Marek