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gcc-plugins/stackleak: Add 'verbose' plugin parameter

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Add 'verbose' plugin parameter for stackleak gcc plugin.
It can be used for printing additional info about the kernel code
instrumentation.

For using it add the following to scripts/Makefile.gcc-plugins:
  gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \
    += -fplugin-arg-stackleak_plugin-verbose

Signed-off-by: Alexander Popov <alex.popov@linux.com>
Link: https://lore.kernel.org/r/20200624123330.83226-6-alex.popov@linux.com
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Alexander Popov 2020-06-24 15:33:30 +03:00 committed by Kees Cook
parent feee1b8c49
commit 8dd70543f7
1 changed files with 42 additions and 5 deletions
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47
scripts/gcc-plugins/stackleak_plugin.c
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@ -34,6 +34,8 @@ __visible int plugin_is_GPL_compatible;
static int track_frame_size = -1;
static bool build_for_x86 = false;
static const char track_function[] = "stackleak_track_stack";
static bool disable = false;
static bool verbose = false;
/*
* Mark these global variables (roots) for gcc garbage collector since
@ -46,6 +48,7 @@ static struct plugin_info stackleak_plugin_info = {
.help = "track-min-size=nn\ttrack stack for functions with a stack frame size >= nn bytes\n"
"arch=target_arch\tspecify target build arch\n"
"disable\t\tdo not activate the plugin\n"
"verbose\t\tprint info about the instrumentation\n"
};
static void add_stack_tracking_gcall(gimple_stmt_iterator *gsi, bool after)
@ -102,6 +105,10 @@ static tree get_current_stack_pointer_decl(void)
return var;
}
if (verbose) {
fprintf(stderr, "stackleak: missing current_stack_pointer in %s()\n",
DECL_NAME_POINTER(current_function_decl));
}
return NULL_TREE;
}
@ -195,6 +202,11 @@ static unsigned int stackleak_instrument_execute(void)
if (!is_alloca(stmt))
continue;
if (verbose) {
fprintf(stderr, "stackleak: be careful, alloca() in %s()\n",
DECL_NAME_POINTER(current_function_decl));
}
/* Insert stackleak_track_stack() call after alloca() */
add_stack_tracking(&gsi, true);
if (bb == entry_bb)
@ -384,13 +396,31 @@ static bool remove_stack_tracking_gasm(void)
*/
static unsigned int stackleak_cleanup_execute(void)
{
const char *fn = DECL_NAME_POINTER(current_function_decl);
bool removed = false;
if (cfun->calls_alloca)
/*
* Leave stack tracking in functions that call alloca().
* Additional case:
* gcc before version 7 called allocate_dynamic_stack_space() from
* expand_stack_vars() for runtime alignment of constant-sized stack
* variables. That caused cfun->calls_alloca to be set for functions
* that in fact don't use alloca().
* For more info see gcc commit 7072df0aae0c59ae437e.
* Let's leave such functions instrumented as well.
*/
if (cfun->calls_alloca) {
if (verbose)
fprintf(stderr, "stackleak: instrument %s(): calls_alloca\n", fn);
return 0;
}
if (large_stack_frame())
/* Leave stack tracking in functions with large stack frame */
if (large_stack_frame()) {
if (verbose)
fprintf(stderr, "stackleak: instrument %s()\n", fn);
return 0;
}
if (lookup_attribute_spec(get_identifier("no_caller_saved_registers")))
removed = remove_stack_tracking_gasm();
@ -516,9 +546,6 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
/* Parse the plugin arguments */
for (i = 0; i < argc; i++) {
if (!strcmp(argv[i].key, "disable"))
return 0;
if (!strcmp(argv[i].key, "track-min-size")) {
if (!argv[i].value) {
error(G_("no value supplied for option '-fplugin-arg-%s-%s'"),
@ -541,6 +568,10 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
if (!strcmp(argv[i].value, "x86"))
build_for_x86 = true;
} else if (!strcmp(argv[i].key, "disable")) {
disable = true;
} else if (!strcmp(argv[i].key, "verbose")) {
verbose = true;
} else {
error(G_("unknown option '-fplugin-arg-%s-%s'"),
plugin_name, argv[i].key);
@ -548,6 +579,12 @@ __visible int plugin_init(struct plugin_name_args *plugin_info,
}
}
if (disable) {
if (verbose)
fprintf(stderr, "stackleak: disabled for this translation unit\n");
return 0;
}
/* Give the information about the plugin */
register_callback(plugin_name, PLUGIN_INFO, NULL,
&stackleak_plugin_info);