1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- Copyright (C) 1988-2023 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Funding Free Software", the Front-Cover
Texts being (a) (see below), and with the Back-Cover Texts being (b)
(see below). A copy of the license is included in the section entitled
"GNU Free Documentation License".
(a) The FSF's Front-Cover Text is:
A GNU Manual
(b) The FSF's Back-Cover Text is:
You have freedom to copy and modify this GNU Manual, like GNU
software. Copies published by the Free Software Foundation raise
funds for GNU development. -->
<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ -->
<head>
<title>GNU Compiler Collection (GCC) Internals: Stack Smashing Protection</title>
<meta name="description" content="GNU Compiler Collection (GCC) Internals: Stack Smashing Protection">
<meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Stack Smashing Protection">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link href="index.html#Top" rel="start" title="Top">
<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="Stack-and-Calling.html#Stack-and-Calling" rel="up" title="Stack and Calling">
<link href="Miscellaneous-Register-Hooks.html#Miscellaneous-Register-Hooks" rel="next" title="Miscellaneous Register Hooks">
<link href="Shrink_002dwrapping-separate-components.html#Shrink_002dwrapping-separate-components" rel="previous" title="Shrink-wrapping separate components">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.indentedblock {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
div.smalllisp {margin-left: 3.2em}
kbd {font-style:oblique}
pre.display {font-family: inherit}
pre.format {font-family: inherit}
pre.menu-comment {font-family: serif}
pre.menu-preformatted {font-family: serif}
pre.smalldisplay {font-family: inherit; font-size: smaller}
pre.smallexample {font-size: smaller}
pre.smallformat {font-family: inherit; font-size: smaller}
pre.smalllisp {font-size: smaller}
span.nocodebreak {white-space:nowrap}
span.nolinebreak {white-space:nowrap}
span.roman {font-family:serif; font-weight:normal}
span.sansserif {font-family:sans-serif; font-weight:normal}
ul.no-bullet {list-style: none}
-->
</style>
</head>
<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
<a name="Stack-Smashing-Protection"></a>
<div class="header">
<p>
Next: <a href="Miscellaneous-Register-Hooks.html#Miscellaneous-Register-Hooks" accesskey="n" rel="next">Miscellaneous Register Hooks</a>, Previous: <a href="Shrink_002dwrapping-separate-components.html#Shrink_002dwrapping-separate-components" accesskey="p" rel="previous">Shrink-wrapping separate components</a>, Up: <a href="Stack-and-Calling.html#Stack-and-Calling" accesskey="u" rel="up">Stack and Calling</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Stack-smashing-protection"></a>
<h4 class="subsection">18.9.15 Stack smashing protection</h4>
<a name="index-stack-smashing-protection"></a>
<dl>
<dt><a name="index-TARGET_005fSTACK_005fPROTECT_005fGUARD"></a>Target Hook: <em>tree</em> <strong>TARGET_STACK_PROTECT_GUARD</strong> <em>(void)</em></dt>
<dd><p>This hook returns a <code>DECL</code> node for the external variable to use
for the stack protection guard. This variable is initialized by the
runtime to some random value and is used to initialize the guard value
that is placed at the top of the local stack frame. The type of this
variable must be <code>ptr_type_node</code>.
</p>
<p>The default version of this hook creates a variable called
‘<samp>__stack_chk_guard</samp>’, which is normally defined in <samp>libgcc2.c</samp>.
</p></dd></dl>
<dl>
<dt><a name="index-TARGET_005fSTACK_005fPROTECT_005fFAIL"></a>Target Hook: <em>tree</em> <strong>TARGET_STACK_PROTECT_FAIL</strong> <em>(void)</em></dt>
<dd><p>This hook returns a <code>CALL_EXPR</code> that alerts the runtime that the
stack protect guard variable has been modified. This expression should
involve a call to a <code>noreturn</code> function.
</p>
<p>The default version of this hook invokes a function called
‘<samp>__stack_chk_fail</samp>’, taking no arguments. This function is
normally defined in <samp>libgcc2.c</samp>.
</p></dd></dl>
<dl>
<dt><a name="index-TARGET_005fSTACK_005fPROTECT_005fRUNTIME_005fENABLED_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_STACK_PROTECT_RUNTIME_ENABLED_P</strong> <em>(void)</em></dt>
<dd><p>Returns true if the target wants GCC’s default stack protect runtime support,
otherwise return false. The default implementation always returns true.
</p></dd></dl>
<dl>
<dt><a name="index-TARGET_005fSUPPORTS_005fSPLIT_005fSTACK"></a>Common Target Hook: <em>bool</em> <strong>TARGET_SUPPORTS_SPLIT_STACK</strong> <em>(bool <var>report</var>, struct gcc_options *<var>opts</var>)</em></dt>
<dd><p>Whether this target supports splitting the stack when the options
described in <var>opts</var> have been passed. This is called
after options have been parsed, so the target may reject splitting
the stack in some configurations. The default version of this hook
returns false. If <var>report</var> is true, this function may issue a warning
or error; if <var>report</var> is false, it must simply return a value
</p></dd></dl>
<dl>
<dt><a name="index-TARGET_005fGET_005fVALID_005fOPTION_005fVALUES"></a>Common Target Hook: <em>vec<const char *></em> <strong>TARGET_GET_VALID_OPTION_VALUES</strong> <em>(int <var>option_code</var>, const char *<var>prefix</var>)</em></dt>
<dd><p>The hook is used for options that have a non-trivial list of
possible option values. OPTION_CODE is option code of opt_code
enum type. PREFIX is used for bash completion and allows an implementation
to return more specific completion based on the prefix. All string values
should be allocated from heap memory and consumers should release them.
The result will be pruned to cases with PREFIX if not NULL.
</p></dd></dl>
<hr>
<div class="header">
<p>
Next: <a href="Miscellaneous-Register-Hooks.html#Miscellaneous-Register-Hooks" accesskey="n" rel="next">Miscellaneous Register Hooks</a>, Previous: <a href="Shrink_002dwrapping-separate-components.html#Shrink_002dwrapping-separate-components" accesskey="p" rel="previous">Shrink-wrapping separate components</a>, Up: <a href="Stack-and-Calling.html#Stack-and-Calling" accesskey="u" rel="up">Stack and Calling</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
</div>
</body>
</html>
|
