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Implement no_stack_protector attribute. 

gcc/ChangeLog:

2020-05-18  Martin Liska  <mliska@suse.cz>

	PR c/94722
	* cfgexpand.c (stack_protect_decl_phase):
	Guard with lookup_attribute("no_stack_protector") at
	various places.
	(expand_used_vars): Likewise here.
	* doc/extend.texi: Document no_stack_protector attribute.

gcc/ada/ChangeLog:

2020-05-18  Martin Liska  <mliska@suse.cz>

	PR c/94722
	* gcc-interface/utils.c (handle_no_stack_protect_attribute):
	New.
	(handle_stack_protect_attribute): Add error message for a
	no_stack_protector function.

gcc/c-family/ChangeLog:

2020-05-18  Martin Liska  <mliska@suse.cz>

	PR c/94722
	* c-attribs.c (handle_no_stack_protect_function_attribute): New.
	(handle_stack_protect_attribute): Add error message for a
	no_stack_protector function.

gcc/testsuite/ChangeLog:

2020-05-18  Martin Liska  <mliska@suse.cz>

	PR c/94722
	* g++.dg/no-stack-protector-attr-2.C: New test.
	* g++.dg/no-stack-protector-attr-3.C: New test.
	* g++.dg/no-stack-protector-attr.C: New test.
This commit is contained in:
Martin Liska 2020-05-15 14:42:12 +02:00
parent 5a99796b85
commit 346b302d09
7 changed files with 154 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
gcc/ada/gcc-interface/utils.c
View File

@ -92,6 +92,7 @@ static tree handle_nonnull_attribute (tree *, tree, tree, int, bool *);
static tree handle_sentinel_attribute (tree *, tree, tree, int, bool *);
static tree handle_noreturn_attribute (tree *, tree, tree, int, bool *);
static tree handle_stack_protect_attribute (tree *, tree, tree, int, bool *);
static tree handle_no_stack_protector_attribute (tree *, tree, tree, int, bool *);
static tree handle_noinline_attribute (tree *, tree, tree, int, bool *);
static tree handle_noclone_attribute (tree *, tree, tree, int, bool *);
static tree handle_noicf_attribute (tree *, tree, tree, int, bool *);
@ -116,6 +117,13 @@ static const struct attribute_spec::exclusions attr_cold_hot_exclusions[] =
{ NULL , false, false, false }
};
static const struct attribute_spec::exclusions attr_stack_protect_exclusions[] =
{
{ "stack_protect", true, false, false },
{ "no_stack_protector", true, false, false },
{ NULL, false, false, false },
};
/* Fake handler for attributes we don't properly support, typically because
they'd require dragging a lot of the common-c front-end circuitry. */
static tree fake_attribute_handler (tree *, tree, tree, int, bool *);
@ -141,7 +149,11 @@ const struct attribute_spec gnat_internal_attribute_table[] =
{ "noreturn", 0, 0, true, false, false, false,
handle_noreturn_attribute, NULL },
{ "stack_protect",0, 0, true, false, false, false,
handle_stack_protect_attribute, NULL },
handle_stack_protect_attribute,
attr_stack_protect_exclusions },
{ "no_stack_protector",0, 0, true, false, false, false,
handle_no_stack_protector_attribute,
attr_stack_protect_exclusions },
{ "noinline", 0, 0, true, false, false, false,
handle_noinline_attribute, NULL },
{ "noclone", 0, 0, true, false, false, false,
@ -6560,6 +6572,23 @@ handle_stack_protect_attribute (tree *node, tree name, tree, int,
return NULL_TREE;
}
/* Handle a "no_stack_protector" attribute; arguments as in
struct attribute_spec.handler. */
static tree
handle_no_stack_protector_attribute (tree *node, tree name, tree, int,
bool *no_add_attrs)
{
if (TREE_CODE (*node) != FUNCTION_DECL)
{
warning (OPT_Wattributes, "%qE attribute ignored", name);
*no_add_attrs = true;
}
return NULL_TREE;
}
/* Handle a "noinline" attribute; arguments as in
struct attribute_spec.handler. */

32
gcc/c-family/c-attribs.c
View File

@ -65,6 +65,8 @@ static tree handle_no_sanitize_undefined_attribute (tree *, tree, tree, int,
static tree handle_asan_odr_indicator_attribute (tree *, tree, tree, int,
bool *);
static tree handle_stack_protect_attribute (tree *, tree, tree, int, bool *);
static tree handle_no_stack_protector_function_attribute (tree *, tree,
tree, int, bool *);
static tree handle_noinline_attribute (tree *, tree, tree, int, bool *);
static tree handle_noclone_attribute (tree *, tree, tree, int, bool *);
static tree handle_nocf_check_attribute (tree *, tree, tree, int, bool *);
@ -248,6 +250,14 @@ static const struct attribute_spec::exclusions attr_noinit_exclusions[] =
ATTR_EXCL (NULL, false, false, false),
};
static const struct attribute_spec::exclusions attr_stack_protect_exclusions[] =
{
ATTR_EXCL ("stack_protect", true, false, false),
ATTR_EXCL ("no_stack_protector", true, false, false),
ATTR_EXCL (NULL, false, false, false),
};
/* Table of machine-independent attributes common to all C-like languages.
Current list of processed common attributes: nonnull. */
@ -275,7 +285,11 @@ const struct attribute_spec c_common_attribute_table[] =
{ "volatile", 0, 0, true, false, false, false,
handle_noreturn_attribute, NULL },
{ "stack_protect", 0, 0, true, false, false, false,
handle_stack_protect_attribute, NULL },
handle_stack_protect_attribute,
attr_stack_protect_exclusions },
{ "no_stack_protector", 0, 0, true, false, false, false,
handle_no_stack_protector_function_attribute,
attr_stack_protect_exclusions },
{ "noinline", 0, 0, true, false, false, false,
handle_noinline_attribute,
attr_noinline_exclusions },
@ -1156,6 +1170,22 @@ handle_stack_protect_attribute (tree *node, tree name, tree, int,
return NULL_TREE;
}
/* Handle a "no_stack_protector" attribute; arguments as in
struct attribute_spec.handler. */
static tree
handle_no_stack_protector_function_attribute (tree *node, tree name, tree,
int, bool *no_add_attrs)
{
if (TREE_CODE (*node) != FUNCTION_DECL)
{
warning (OPT_Wattributes, "%qE attribute ignored", name);
*no_add_attrs = true;
}
return NULL_TREE;
}
/* Handle a "noipa" attribute; arguments as in
struct attribute_spec.handler. */

82
gcc/cfgexpand.c
View File

@ -1831,11 +1831,12 @@ stack_protect_decl_phase (tree decl)
if (bits & SPCT_HAS_SMALL_CHAR_ARRAY)
has_short_buffer = true;
if (flag_stack_protect == SPCT_FLAG_ALL
|| flag_stack_protect == SPCT_FLAG_STRONG
|| (flag_stack_protect == SPCT_FLAG_EXPLICIT
&& lookup_attribute ("stack_protect",
DECL_ATTRIBUTES (current_function_decl))))
tree attribs = DECL_ATTRIBUTES (current_function_decl);
if (!lookup_attribute ("no_stack_protector", attribs)
&& (flag_stack_protect == SPCT_FLAG_ALL
|| flag_stack_protect == SPCT_FLAG_STRONG
|| (flag_stack_protect == SPCT_FLAG_EXPLICIT
&& lookup_attribute ("stack_protect", attribs))))
{
if ((bits & (SPCT_HAS_SMALL_CHAR_ARRAY | SPCT_HAS_LARGE_CHAR_ARRAY))
&& !(bits & SPCT_HAS_AGGREGATE))
@ -2136,6 +2137,7 @@ expand_used_vars (void)
set are actually used by the optimized function. Lay them out. */
expand_used_vars_for_block (outer_block, true);
tree attribs = DECL_ATTRIBUTES (current_function_decl);
if (stack_vars_num > 0)
{
bool has_addressable_vars = false;
@ -2145,10 +2147,10 @@ expand_used_vars (void)
/* If stack protection is enabled, we don't share space between
vulnerable data and non-vulnerable data. */
if (flag_stack_protect != 0
&& !lookup_attribute ("no_stack_protector", attribs)
&& (flag_stack_protect != SPCT_FLAG_EXPLICIT
|| (flag_stack_protect == SPCT_FLAG_EXPLICIT
&& lookup_attribute ("stack_protect",
DECL_ATTRIBUTES (current_function_decl)))))
&& lookup_attribute ("stack_protect", attribs))))
has_addressable_vars = add_stack_protection_conflicts ();
if (flag_stack_protect == SPCT_FLAG_STRONG && has_addressable_vars)
@ -2161,38 +2163,40 @@ expand_used_vars (void)
dump_stack_var_partition ();
}
switch (flag_stack_protect)
{
case SPCT_FLAG_ALL:
create_stack_guard ();
break;
case SPCT_FLAG_STRONG:
if (gen_stack_protect_signal
|| cfun->calls_alloca
|| has_protected_decls
|| lookup_attribute ("stack_protect",
DECL_ATTRIBUTES (current_function_decl)))
if (!lookup_attribute ("no_stack_protector", attribs))
switch (flag_stack_protect)
{
case SPCT_FLAG_ALL:
create_stack_guard ();
break;
break;
case SPCT_FLAG_DEFAULT:
if (cfun->calls_alloca
|| has_protected_decls
|| lookup_attribute ("stack_protect",
DECL_ATTRIBUTES (current_function_decl)))
create_stack_guard ();
break;
case SPCT_FLAG_STRONG:
if (gen_stack_protect_signal
|| cfun->calls_alloca
|| has_protected_decls
|| lookup_attribute ("stack_protect",
DECL_ATTRIBUTES (current_function_decl)))
create_stack_guard ();
break;
case SPCT_FLAG_EXPLICIT:
if (lookup_attribute ("stack_protect",
DECL_ATTRIBUTES (current_function_decl)))
create_stack_guard ();
break;
case SPCT_FLAG_DEFAULT:
if (cfun->calls_alloca
|| has_protected_decls
|| lookup_attribute ("stack_protect",
DECL_ATTRIBUTES (current_function_decl)))
create_stack_guard ();
break;
default:
break;
}
case SPCT_FLAG_EXPLICIT:
if (lookup_attribute ("stack_protect",
DECL_ATTRIBUTES (current_function_decl)))
create_stack_guard ();
break;
default:
break;
}
/* Assign rtl to each variable based on these partitions. */
if (stack_vars_num > 0)
@ -2213,11 +2217,11 @@ expand_used_vars (void)
expand_stack_vars (stack_protect_decl_phase_1, &data);
/* Phase 2 contains other kinds of arrays. */
if (flag_stack_protect == SPCT_FLAG_ALL
|| flag_stack_protect == SPCT_FLAG_STRONG
|| (flag_stack_protect == SPCT_FLAG_EXPLICIT
&& lookup_attribute ("stack_protect",
DECL_ATTRIBUTES (current_function_decl))))
if (!lookup_attribute ("no_stack_protector", attribs)
&& (flag_stack_protect == SPCT_FLAG_ALL
|| flag_stack_protect == SPCT_FLAG_STRONG
|| (flag_stack_protect == SPCT_FLAG_EXPLICIT
&& lookup_attribute ("stack_protect", attribs))))
expand_stack_vars (stack_protect_decl_phase_2, &data);
}

4
gcc/doc/extend.texi
View File

@ -3680,6 +3680,10 @@ This attribute adds stack protection code to the function if
flags @option{-fstack-protector}, @option{-fstack-protector-strong}
or @option{-fstack-protector-explicit} are set.
@item no_stack_protector
@cindex @code{no_stack_protector} function attribute
This attribute prevents stack protection code for the function.
@item target (@var{string}, @dots{})
@cindex @code{target} function attribute
Multiple target back ends implement the @code{target} attribute

7
gcc/testsuite/g++.dg/no-stack-protector-attr-2.C Normal file
View File

@ -0,0 +1,7 @@
/* PR c/94722 */
/* { dg-do compile } */
int __attribute__((no_stack_protector, stack_protect)) c() /* { dg-warning "ignoring attribute 'stack_protect' because it conflicts with attribute 'no_stack_protector'" } */
{
return 0;
}

23
gcc/testsuite/g++.dg/no-stack-protector-attr-3.C Normal file
View File

@ -0,0 +1,23 @@
/* PR c/94722 */
/* Test that stack protection is disabled via no_stack_protector attribute. */
/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
/* { dg-options "-O2 -fstack-protector-explicit" } */
/* { dg-do compile } */
int __attribute__((no_stack_protector)) foo()
{
int a;
char b[34];
return 0;
}
int __attribute__((stack_protect)) bar()
{
int a;
char b[34];
return 0;
}
/* { dg-final { scan-assembler-times "stack_chk_fail" 1 } } */

16
gcc/testsuite/g++.dg/no-stack-protector-attr.C Normal file
View File

@ -0,0 +1,16 @@
/* PR c/94722 */
/* Test that stack protection is disabled via no_stack_protector attribute. */
/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
/* { dg-options "-O2 -fstack-protector-all" } */
/* { dg-do compile } */
int __attribute__((no_stack_protector)) c()
{
int a;
char b[34];
return 0;
}
/* { dg-final { scan-assembler-not "stack_chk_fail" } } */