From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-il1-f198.google.com (mail-il1-f198.google.com [209.85.166.198]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8A7308614E for ; Sat, 2 Nov 2024 22:01:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.198 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730584862; cv=none; b=vCUlYYvkZWijVpvuP6GHyDw5mb6basq6eoUyfYOW0fludeGBlUCx/Lfqo88otQlPJGCEYt+KtHxhwU13jrZT8STM394JJt2a/JzLPy5SjsvaDaXkMzgoxPESw+RNl4HAGu5q/WIh42azWHGHl2gshujPEXN8S6DS8fwXBjbjFOA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730584862; c=relaxed/simple; bh=m6O7JVK2Y4NC2c2KWZjmfat94ZO0QYtS8+D81hBby60=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; b=RQx+CjYatmE19mHkdS0+T6BkeAFt8Y1cmN7PMjrF/6wvmENcSlruB+SDriPZPZuOXxE1tLipQNovNyzzEfnkBC1LlE4k5BfunCjD9T5gVOy//9SMgyweI+6ajBrkASdVHy5tQ0+OiIWXnYFvBl1yJjLDwbzdxNn+nO4xFMBq82o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.166.198 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-il1-f198.google.com with SMTP id e9e14a558f8ab-3a6c48f1312so4540075ab.3 for ; Sat, 02 Nov 2024 15:01:00 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1730584859; x=1731189659; h=to:from:subject:message-id:in-reply-to:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=v8tbj7e9k237S9KGvUBtD9qU/B90mL+uE91vmCaf7MQ=; b=Bb8/GnCO2FAfjffo6axtp1kz5XdUZXlxWWrxwWqx8Nqx9QyLmfsHXN1To5KA7MY3Rf 0BfIH3UYOX+7Ms1cjVXjedJ/DXF9PS+hKBX+9f0VHMmAbE4lm6KF1M+YJV+v6SU7Rkem YZ0J4TQUk2ZDVLgPNNsvK+yV1ponh3bRWOsOsKPXIfWadihse9PxaGtQ17VY658Md3LL A9d7tiyjvX+E6TtBvLlzOHjPE3cYIbfPB6QGhfqxtMQkYA9fzNk+vbu5Pv3SgIPkNPc5 25tUOULkPIehPQdLnlxAXyA+QMML1SKnBccOE7Uof7vKp0XZQo2BRZ8w6+Q4M8SgCBj/ hc4Q== X-Gm-Message-State: AOJu0YxHGT0AU6vFabBS6otdI2IIB/oIf3h2wIyt5er5ctLcI3Aysaz4 9ko8JNXY+1SlMIgbhUPFmqch1zdW+sW3wBIji+jml38eh7EcO1/SFqnCbCWQskJE7Vcyd+aG4iz bu4lt7dAUXcAU1PHzmolrKp0LHRkJMV93JYdPEMgk33b0IKP7aM9GO8U= X-Google-Smtp-Source: AGHT+IEP6+rDKbplC5ep0NypEj4o99iM1dTORM/McG7tQQMcgDXy2dOuyj7U2Vd64CeGuCr28DWUQhh8oMqWhOvLPwAsT5X1Jafg Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6e02:152e:b0:3a6:b445:dc9c with SMTP id e9e14a558f8ab-3a6b445decemr58449385ab.3.1730584859431; Sat, 02 Nov 2024 15:00:59 -0700 (PDT) Date: Sat, 02 Nov 2024 15:00:59 -0700 In-Reply-To: <0000000000003c68f3061fd2c285@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6726a11b.050a0220.35b515.0189.GAE@google.com> Subject: Re: [syzbot] [PATCH] usb: raw_gadget: Fix a KASAN double-free bug in raw_release From: syzbot To: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org. *** Subject: [PATCH] usb: raw_gadget: Fix a KASAN double-free bug in raw_release Author: marcus.yu.56@gmail.com #syz test syzkaller reported a double free bug (https://syzkaller.appspot.com/bug?extid=3e563d99e70973c0755c) in raw_release. I suspect this is because a race between raw_release and raw_ioctl_run. While kref_get in raw_ioctl_run is protected by the spin lock, all kref_put in raw_release are not under the lock. This makes it possible that a kref_put might occur during kref_get, which is specifically prohibited by the kref documentation[1]. The fix is to ensure that all kref_put calls are made under lock and that we only call kfree(dev) after releasing the lock. [1] https://docs.kernel.org/core-api/kref.html Signed-off-by: Chang Yu Reported-by: syzbot+3e563d99e70973c0755c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3e563d99e70973c0755c Fixes: f2c2e717642c ("usb: gadget: add raw-gadget interface") --- drivers/usb/gadget/legacy/raw_gadget.c | 44 ++++++++++++++------------ 1 file changed, 24 insertions(+), 20 deletions(-) diff --git a/drivers/usb/gadget/legacy/raw_gadget.c b/drivers/usb/gadget/legacy/raw_gadget.c index 112fd18d8c99..0c01d491d489 100644 --- a/drivers/usb/gadget/legacy/raw_gadget.c +++ b/drivers/usb/gadget/legacy/raw_gadget.c @@ -225,7 +225,6 @@ static void dev_free(struct kref *kref) kfree(dev->eps[i].ep->desc); dev->eps[i].state = STATE_EP_DISABLED; } - kfree(dev); } /*----------------------------------------------------------------------*/ @@ -330,7 +329,8 @@ static void gadget_unbind(struct usb_gadget *gadget) set_gadget_data(gadget, NULL); /* Matches kref_get() in gadget_bind(). */ - kref_put(&dev->count, dev_free); + if (kref_put(&dev->count, dev_free)) + kfree(dev); } static int gadget_setup(struct usb_gadget *gadget, @@ -443,34 +443,38 @@ static int raw_open(struct inode *inode, struct file *fd) static int raw_release(struct inode *inode, struct file *fd) { int ret = 0; + int freed = 0; struct raw_dev *dev = fd->private_data; unsigned long flags; - bool unregister = false; spin_lock_irqsave(&dev->lock, flags); dev->state = STATE_DEV_CLOSED; - if (!dev->gadget) { - spin_unlock_irqrestore(&dev->lock, flags); - goto out_put; - } - if (dev->gadget_registered) - unregister = true; + if (!dev->gadget) + goto out_put_locked; + if (!dev->gadget_registered) + goto out_put_locked; dev->gadget_registered = false; spin_unlock_irqrestore(&dev->lock, flags); - if (unregister) { - ret = usb_gadget_unregister_driver(&dev->driver); - if (ret != 0) - dev_err(dev->dev, - "usb_gadget_unregister_driver() failed with %d\n", - ret); - /* Matches kref_get() in raw_ioctl_run(). */ - kref_put(&dev->count, dev_free); - } + ret = usb_gadget_unregister_driver(&dev->driver); + if (ret != 0) + dev_err(dev->dev, + "usb_gadget_unregister_driver() failed with %d\n", + ret); + + spin_lock_irqsave(&dev->lock, flags); + /* Matches kref_get() in raw_ioctl_run(). */ + freed = kref_put(&dev->count, dev_free); + if (freed) + goto out_free_dev; -out_put: +out_put_locked: /* Matches dev_new() in raw_open(). */ - kref_put(&dev->count, dev_free); + freed = kref_put(&dev->count, dev_free); +out_free_dev: + spin_unlock_irqrestore(&dev->lock, flags); + if (freed) + kfree(dev); return ret; } -- 2.47.0