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Commit eb910947 authored by Brian Norris's avatar Brian Norris Committed by Shuah Khan
Browse files

test: firmware_class: add asynchronous request trigger 



We might want to test for bugs like that found in commit f9692b26
("firmware: fix possible use after free on name on asynchronous
request"), where the asynchronous request API had race conditions.

Let's add a simple file that will launch the async request, then wait
until it's complete and report the status. It's not a true async test
(we're using a mutex + wait_for_completion(), so we can't get more than
one going at the same time), but it does help make sure the basic API is
sane, and it can catch some class of bugs.

Signed-off-by: default avatarBrian Norris <computersforpeace@gmail.com>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarShuah Khan <shuahkh@osg.samsung.com>
parent be4a1326

lib/test_firmware.c

+65 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <linux/init.h>

#include <linux/module.h>

#include <linux/printk.h>

#include <linux/completion.h>

#include <linux/firmware.h>

#include <linux/device.h>

#include <linux/fs.h>
@@ -80,6 +81,57 @@ static ssize_t trigger_request_store(struct device *dev, 
}

static DEVICE_ATTR_WO(trigger_request);



static DECLARE_COMPLETION(async_fw_done);



static void trigger_async_request_cb(const struct firmware *fw, void *context)

{

	test_firmware = fw;

	complete(&async_fw_done);

}



static ssize_t trigger_async_request_store(struct device *dev,

					   struct device_attribute *attr,

					   const char *buf, size_t count)

{

	int rc;

	char *name;



	name = kstrndup(buf, count, GFP_KERNEL);

	if (!name)

		return -ENOSPC;



	pr_info("loading '%s'\n", name);



	mutex_lock(&test_fw_mutex);

	release_firmware(test_firmware);

	test_firmware = NULL;

	rc = request_firmware_nowait(THIS_MODULE, 1, name, dev, GFP_KERNEL,

				     NULL, trigger_async_request_cb);

	if (rc) {

		pr_info("async load of '%s' failed: %d\n", name, rc);

		kfree(name);

		goto out;

	}

	/* Free 'name' ASAP, to test for race conditions */

	kfree(name);



	wait_for_completion(&async_fw_done);



	if (test_firmware) {

		pr_info("loaded: %zu\n", test_firmware->size);

		rc = count;

	} else {

		pr_err("failed to async load firmware\n");

		rc = -ENODEV;

	}



out:

	mutex_unlock(&test_fw_mutex);



	return rc;

}

static DEVICE_ATTR_WO(trigger_async_request);



static int __init test_firmware_init(void)

{

	int rc;
@@ -96,9 +148,20 @@ static int __init test_firmware_init(void) 
		goto dereg;

	}



	rc = device_create_file(test_fw_misc_device.this_device,

				&dev_attr_trigger_async_request);

	if (rc) {

		pr_err("could not create async sysfs interface: %d\n", rc);

		goto remove_file;

	}



	pr_warn("interface ready\n");



	return 0;



remove_file:

	device_remove_file(test_fw_misc_device.this_device,

			   &dev_attr_trigger_async_request);

dereg:

	misc_deregister(&test_fw_misc_device);

	return rc;
@@ -109,6 +172,8 @@ module_init(test_firmware_init); 
static void __exit test_firmware_exit(void)

{

	release_firmware(test_firmware);

	device_remove_file(test_fw_misc_device.this_device,

			   &dev_attr_trigger_async_request);

	device_remove_file(test_fw_misc_device.this_device,

			   &dev_attr_trigger_request);

	misc_deregister(&test_fw_misc_device);