From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3F9636ADB for ; Fri, 10 Mar 2023 13:44:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63F9EC433D2; Fri, 10 Mar 2023 13:44:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678455891; bh=0sMP6g/a/9ZpoYbQSM8nb0evnlGRG2epWHW6D+u5S8I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=A7R1xrmWNoQbCC8agtn4mM7xx/OM7NGWCEc4k9feCTy4in1XLm3v5E7fJTKJfOIqs sKPnUTSW5fofvDc06AUXahj7mkwONJK26D7Ws+ya80ZOcxFkYQ4VZFDQLffNHvnzYf ZdLEye5DFUWdl8jkivQCxTbn46cO8qXswu6sDYA4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Alan Stern , Troels Liebe Bentsen Subject: [PATCH 4.14 011/193] USB: core: Dont hold device lock while reading the "descriptors" sysfs file Date: Fri, 10 Mar 2023 14:36:33 +0100 Message-Id: <20230310133711.307709237@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230310133710.926811681@linuxfoundation.org> References: <20230310133710.926811681@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Alan Stern commit 45bf39f8df7f05efb83b302c65ae3b9bc92b7065 upstream. Ever since commit 83e83ecb79a8 ("usb: core: get config and string descriptors for unauthorized devices") was merged in 2013, there has been no mechanism for reallocating the rawdescriptors buffers in struct usb_device after the initial enumeration. Before that commit, the buffers would be deallocated when a device was deauthorized and reallocated when it was authorized and enumerated. This means that the locking in the read_descriptors() routine is not needed, since the buffers it reads will never be reallocated while the routine is running. This locking can interfere with user programs trying to read a hub's descriptors via sysfs while new child devices of the hub are being initialized, since the hub is locked during this procedure. Since the locking in read_descriptors() hasn't been needed for over nine years, we can remove it. Reported-and-tested-by: Troels Liebe Bentsen Signed-off-by: Alan Stern CC: stable@vger.kernel.org Link: https://lore.kernel.org/r/Y9l+wDTRbuZABzsE@rowland.harvard.edu Signed-off-by: Greg Kroah-Hartman --- drivers/usb/core/hub.c | 5 ++--- drivers/usb/core/sysfs.c | 5 ----- 2 files changed, 2 insertions(+), 8 deletions(-) --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -2322,9 +2322,8 @@ static int usb_enumerate_device_otg(stru * usb_enumerate_device - Read device configs/intfs/otg (usbcore-internal) * @udev: newly addressed device (in ADDRESS state) * - * This is only called by usb_new_device() and usb_authorize_device() - * and FIXME -- all comments that apply to them apply here wrt to - * environment. + * This is only called by usb_new_device() -- all comments that apply there + * apply here wrt to environment. * * If the device is WUSB and not authorized, we don't attempt to read * the string descriptors, as they will be errored out by the device --- a/drivers/usb/core/sysfs.c +++ b/drivers/usb/core/sysfs.c @@ -865,11 +865,7 @@ read_descriptors(struct file *filp, stru size_t srclen, n; int cfgno; void *src; - int retval; - retval = usb_lock_device_interruptible(udev); - if (retval < 0) - return -EINTR; /* The binary attribute begins with the device descriptor. * Following that are the raw descriptor entries for all the * configurations (config plus subsidiary descriptors). @@ -894,7 +890,6 @@ read_descriptors(struct file *filp, stru off -= srclen; } } - usb_unlock_device(udev); return count - nleft; }