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test: firmware_class: add asynchronous request trigger

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We might want to test for bugs like that found in commit f9692b2699
("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: Brian Norris <computersforpeace@gmail.com>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
This commit is contained in:
Brian Norris 2015-12-09 14:50:27 -08:00 committed by Shuah Khan
parent be4a1326d1
commit eb910947c8
1 changed files with 65 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

65
lib/test_firmware.c
View file

@ -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);