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Re: [4.7][google] Adding a new option -fstack-protector-strong. (issue5461043)
Hi, Andrew and Richard, check via referenced vars is much easier, thanks!
Updated patches attached at EOM, also uploaded to
http://codereview.appspot.com/5461043
Hi, Diego, that's good suggestion. I'm glad to send this for trunk at
the next stage 1.
-Han
Updated patches ================
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index 8684721..ae76441 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -1507,15 +1507,34 @@ estimated_stack_frame_size (struct cgraph_node *node)
return size;
}
+/* Helper routine to check if a record or union contains an array field. */
+
+static int record_or_union_type_has_array(tree tree_type) {
+ tree fields = TYPE_FIELDS(tree_type);
+ tree f;
+ for (f = fields; f; f = DECL_CHAIN (f)) {
+ if (TREE_CODE(f) == FIELD_DECL) {
+ tree field_type = TREE_TYPE(f);
+ if (RECORD_OR_UNION_TYPE_P(field_type))
+ return record_or_union_type_has_array(field_type);
+ if (TREE_CODE(field_type) == ARRAY_TYPE)
+ return 1;
+ }
+ }
+ return 0;
+}
+
/* Expand all variables used in the function. */
static void
expand_used_vars (void)
{
tree var, outer_block = DECL_INITIAL (current_function_decl);
+ referenced_var_iterator rvi;
VEC(tree,heap) *maybe_local_decls = NULL;
unsigned i;
unsigned len;
+ int gen_stack_protect_signal = 0;
/* Compute the phase of the stack frame for this function. */
{
@@ -1548,6 +1567,20 @@ expand_used_vars (void)
}
}
+ FOR_EACH_REFERENCED_VAR(DECL_STRUCT_FUNCTION(current_function_decl),
var, rvi)
+ if (!is_global_var(var) && TREE_ADDRESSABLE(var))
+ ++gen_stack_protect_signal;
+
+ /* Examine local variable declaration. */
+ if (!gen_stack_protect_signal)
+ FOR_EACH_LOCAL_DECL (cfun, i, var)
+ if (TREE_CODE(var) == VAR_DECL && !is_global_var(var)) {
+ tree var_type = TREE_TYPE(var);
+ gen_stack_protect_signal += (TREE_CODE(var_type) == ARRAY_TYPE) ||
+ (RECORD_OR_UNION_TYPE_P(var_type) &&
+ record_or_union_type_has_array(var_type));
+ }
+
/* At this point all variables on the local_decls with TREE_USED
set are not associated with any block scope. Lay them out. */
@@ -1640,9 +1673,13 @@ expand_used_vars (void)
/* There are several conditions under which we should create a
stack guard: protect-all, alloca used, protected decls present. */
- if (flag_stack_protect == 2
- || (flag_stack_protect
- && (cfun->calls_alloca || has_protected_decls)))
+ if (flag_stack_protect == 2 /* -fstack-protector-all */
+ || (flag_stack_protect == 1 /* -fstack-protector */
+ && (cfun->calls_alloca || has_protected_decls))) {
+ create_stack_guard ();
+ } else if (flag_stack_protect == 3 && /* -fstack-protector-strong */
+ (gen_stack_protect_signal ||
+ cfun->calls_alloca || has_protected_decls))
create_stack_guard ();
/* Assign rtl to each variable based on these partitions. */
diff --git a/gcc/common.opt b/gcc/common.opt
index 55d3f2d..1ad9717 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -1848,6 +1848,10 @@ fstack-protector-all
Common Report RejectNegative Var(flag_stack_protect, 2)
Use a stack protection method for every function
+fstack-protector-strong
+Common Report RejectNegative Var(flag_stack_protect, 3)
+Use a smart stack protection method for certain functions
+
fstack-usage
Common RejectNegative Var(flag_stack_usage)
Output stack usage information on a per-function basis
diff --git a/gcc/testsuite/gcc.dg/fstack-protector-strong.c
b/gcc/testsuite/gcc.dg/fstack-protector-strong.c
new file mode 100644
index 0000000..44225f5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/fstack-protector-strong.c
@@ -0,0 +1,110 @@
+/* Test that stack protection is done on chosen functions. */
+
+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-O2 -fstack-protector-strong" } */
+
+#include<string.h>
+#include<stdlib.h>
+
+extern int g0;
+extern int *pg0;
+int goo(int *);
+int hoo(int);
+
+/* Function frame address escaped function call. */
+int foo1()
+{
+ int i;
+ return goo(&i);
+}
+
+struct ArrayStruct {
+ int a;
+ int array[10];
+};
+
+struct AA {
+ int b;
+ struct ArrayStruct as;
+};
+
+/* Function frame contains array. */
+int foo2() {
+ struct AA aa;
+ int i;
+ for (i = 0; i < 10; ++i) {
+ aa.as.array[i] = i * (i-1) + i / 2;
+ }
+ return aa.as.array[5];
+}
+
+/* Address computation based on a function frame address. */
+int foo3() {
+ int a;
+ int *p;
+ p = &a + 5;
+ return goo(p);
+}
+
+/* Address cast based on a function frame address. */
+int foo4() {
+ int a;
+ return goo(g0 << 2 ? (int *)(3 * (long)(void *)(&a)) : 0);
+
+}
+
+/* Address cast based on a local array. */
+int foo5() {
+ short array[10];
+ return goo((int *)(array + 5));
+}
+
+struct BB {
+ int one;
+ int two;
+ int three;
+};
+
+/* Address computaton based on a function frame address.*/
+int foo6() {
+ struct BB bb;
+ return goo(&bb.one + sizeof(int));
+}
+
+/* Function frame address escaped via global variable. */
+int foo7() {
+ int a;
+ pg0 = &a;
+ goo(pg0);
+ return *pg0;
+}
+
+/* Check that this covers -fstack-protector. */
+int foo8() {
+ char base[100];
+ memcpy((void *)base, (const void *)pg0, 105);
+ return (int)(base[32]);
+}
+
+/* Check that this covers -fstack-protector. */
+int foo9() {
+ char* p = alloca(100);
+ return goo((int *)(p + 50));
+}
+
+/* Address taken on struct. */
+int foo10() {
+ struct BB bb;
+ int i;
+ memset(&bb, 5, sizeof bb);
+ for (i = 0; i < 10; ++i) {
+ bb.one = i;
+ bb.two = bb.one + bb.two;
+ bb.three = bb.one + bb.two + bb.three;
+ }
+ return bb.three;
+}
+
+/* { dg-final { scan-assembler-times "stack_chk_fail" 10 } } */
+
+
================================
On Thu, Dec 8, 2011 at 5:18 AM, Diego Novillo <dnovillo@google.com> wrote:
> On Wed, Dec 7, 2011 at 20:07, Han Shen <shenhan@google.com> wrote:
>
>> Status - implemented internally, to be up-streamed or merged to google branch only.
>
> Why would you not consider sending this for trunk at the next stage 1?
>
> (patch review in progress)
>
> Diego.