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Commit 4f6de4d5 authored by Mathias Krause's avatar Mathias Krause Committed by Rusty Russell
Browse files

module: don't modify argument of module_kallsyms_lookup_name() 



If we pass a pointer to a const string in the form "module:symbol"
module_kallsyms_lookup_name() will try to split the string at the colon,
i.e., will try to modify r/o data. That will, in fact, fail on a kernel
with enabled CONFIG_DEBUG_RODATA.

Avoid modifying the passed string in module_kallsyms_lookup_name(),
modify find_module_all() instead to pass it the module name length.

Signed-off-by: default avatarMathias Krause <minipli@googlemail.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 06df44ee

kernel/module.c

+7 −8
Original line number Original line Diff line number Diff line
@@ -455,7 +455,7 @@ const struct kernel_symbol *find_symbol(const char *name, 
EXPORT_SYMBOL_GPL(find_symbol);

EXPORT_SYMBOL_GPL(find_symbol);





/* Search for module by name: must hold module_mutex. */

/* Search for module by name: must hold module_mutex. */

static struct module *find_module_all(const char *name,

static struct module *find_module_all(const char *name, size_t len,

				      bool even_unformed)

				      bool even_unformed)

{

{

	struct module *mod;

	struct module *mod;
@@ -463,7 +463,7 @@ static struct module *find_module_all(const char *name, 
	list_for_each_entry(mod, &modules, list) {

	list_for_each_entry(mod, &modules, list) {

		if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)

		if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)

			continue;

			continue;

		if (strcmp(mod->name, name) == 0)

		if (strlen(mod->name) == len && !memcmp(mod->name, name, len))

			return mod;

			return mod;

	}

	}

	return NULL;

	return NULL;
@@ -471,7 +471,7 @@ static struct module *find_module_all(const char *name, 




struct module *find_module(const char *name)

struct module *find_module(const char *name)

{

{

	return find_module_all(name, false);

	return find_module_all(name, strlen(name), false);

}

}

EXPORT_SYMBOL_GPL(find_module);

EXPORT_SYMBOL_GPL(find_module);
@@ -3027,7 +3027,7 @@ static bool finished_loading(const char *name) 
	bool ret;

	bool ret;





	mutex_lock(&module_mutex);

	mutex_lock(&module_mutex);

	mod = find_module_all(name, true);

	mod = find_module_all(name, strlen(name), true);

	ret = !mod || mod->state == MODULE_STATE_LIVE

	ret = !mod || mod->state == MODULE_STATE_LIVE

		|| mod->state == MODULE_STATE_GOING;

		|| mod->state == MODULE_STATE_GOING;

	mutex_unlock(&module_mutex);

	mutex_unlock(&module_mutex);
@@ -3165,7 +3165,8 @@ static int add_unformed_module(struct module *mod) 




again:

again:

	mutex_lock(&module_mutex);

	mutex_lock(&module_mutex);

	if ((old = find_module_all(mod->name, true)) != NULL) {

	old = find_module_all(mod->name, strlen(mod->name), true);

	if (old != NULL) {

		if (old->state == MODULE_STATE_COMING

		if (old->state == MODULE_STATE_COMING

		    || old->state == MODULE_STATE_UNFORMED) {

		    || old->state == MODULE_STATE_UNFORMED) {

			/* Wait in case it fails to load. */

			/* Wait in case it fails to load. */
@@ -3576,10 +3577,8 @@ unsigned long module_kallsyms_lookup_name(const char *name) 
	/* Don't lock: we're in enough trouble already. */

	/* Don't lock: we're in enough trouble already. */

	preempt_disable();

	preempt_disable();

	if ((colon = strchr(name, ':')) != NULL) {

	if ((colon = strchr(name, ':')) != NULL) {

		*colon = '\0';

		if ((mod = find_module_all(name, colon - name, false)) != NULL)

		if ((mod = find_module(name)) != NULL)

			ret = mod_find_symname(mod, colon+1);

			ret = mod_find_symname(mod, colon+1);

		*colon = ':';

	} else {

	} else {

		list_for_each_entry_rcu(mod, &modules, list) {

		list_for_each_entry_rcu(mod, &modules, list) {

			if (mod->state == MODULE_STATE_UNFORMED)

			if (mod->state == MODULE_STATE_UNFORMED)