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From: Hillf Danton <hdanton@sina.com>
To: syzbot <syzbot+2f44671e54488d20f0e6@syzkaller.appspotmail.com>
Cc: linux-kernel@vger.kernel.org,
	syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [kernfs?] [usb?] WARNING in kernfs_get (5)
Date: Wed, 15 May 2024 18:33:25 +0800
Message-Id: <20240515103325.3308-1-hdanton@sina.com>
In-Reply-To: <0000000000007224f506186be18b@google.com>
References: 
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On Tue, 14 May 2024 08:44:43 -0700
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    26dd54d03cd9 Add linux-next specific files for 20240514
> git tree:       linux-next
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14b06900980000

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git  26dd54d03cd9

--- l/drivers/base/firmware_loader/fallback.c
+++ f/drivers/base/firmware_loader/fallback.c
@@ -83,15 +83,15 @@ static int fw_load_sysfs_fallback(struct
 
 	dev_set_uevent_suppress(f_dev, true);
 
+	mutex_lock(&fw_lock);
+
 	retval = device_add(f_dev);
 	if (retval) {
 		dev_err(f_dev, "%s: device_register failed\n", __func__);
 		goto err_put_dev;
 	}
 
-	mutex_lock(&fw_lock);
 	if (fw_load_abort_all || fw_state_is_aborted(fw_priv)) {
-		mutex_unlock(&fw_lock);
 		retval = -EINTR;
 		goto out;
 	}
@@ -120,10 +120,12 @@ static int fw_load_sysfs_fallback(struct
 	} else if (fw_priv->is_paged_buf && !fw_priv->data)
 		retval = -ENOMEM;
 
+	mutex_lock(&fw_lock);
 out:
 	device_del(f_dev);
 err_put_dev:
 	put_device(f_dev);
+	mutex_unlock(&fw_lock);
 	return retval;
 }
 
--- l/drivers/base/firmware_loader/sysfs.c
+++ s/drivers/base/firmware_loader/sysfs.c
@@ -81,10 +81,8 @@ static int firmware_uevent(const struct
 	const struct fw_sysfs *fw_sysfs = to_fw_sysfs(dev);
 	int err = 0;
 
-	mutex_lock(&fw_lock);
 	if (fw_sysfs->fw_priv)
 		err = do_firmware_uevent(fw_sysfs, env);
-	mutex_unlock(&fw_lock);
 	return err;
 }
 #endif /* CONFIG_FW_LOADER_USER_HELPER */
--