test: firmware_class: add asynchronous request trigger

We might want to test for bugs like that found in commit f9692b2699bd
("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>

1 files changed, 65 insertions, 0 deletions

diff --git a/lib/test_firmware.c b/lib/test_firmware.c
index 690b9c35a274..a3e8ec3fb1c5 100644
--- a/lib/test_firmware.c
+++ b/lib/test_firmware.c
@@ -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 @@ out:
 }
 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;
@@ -110,6 +173,8 @@ 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);
         pr_warn("removed interface\n");