From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750996AbdANDlO (ORCPT ); Fri, 13 Jan 2017 22:41:14 -0500 Received: from mx4.wp.pl ([212.77.101.12]:52837 "EHLO mx4.wp.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750750AbdANDlN (ORCPT ); Fri, 13 Jan 2017 22:41:13 -0500 Date: Fri, 13 Jan 2017 19:40:50 -0800 From: Jakub Kicinski To: Daniel Wagner , Bjorn Andersson Cc: "Luis R. Rodriguez" , linux-kernel@vger.kernel.org Subject: Re: 4.10-rc3, firmware loading via user space helper crashes if firmware not present Message-ID: <20170113194050.48fa5e0b@laptop> In-Reply-To: <20170113133258.1cc6bf39@laptop> References: <20170113133258.1cc6bf39@laptop> X-Mailer: Claws Mail 3.14.0-49-g1cc35f (GTK+ 2.24.31; x86_64-unknown-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-WP-MailID: 0df986e5b7ca4df92d7cc96fd1b8642f X-WP-AV: skaner antywirusowy Poczty Wirtualnej Polski X-WP-SPAM: NO 000000A [AdMk] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 13 Jan 2017 13:32:58 -0800, Jakub Kicinski wrote: > If one requests a FW which does not exist in the FS and the user space > helper is used then fw_load_abort() will be called twice which leads to > NULL-deref. > > It will be called once in firmware_loading_store() (handling the -1 > case) and then again in _request_firmware_load() because return value > from fw_state_wait_timeout() was negative. > > I think this is introduced in by f52cc379423d ("firmware: refactor > loading status"). > > The simple fix would be to not "unlink" the buf by fw_load_abort() in > firmware_loading_store() and always rely on firmware_loading_store(). > > ------->8------------------------------------ > > diff --git a/drivers/base/firmware_class.c > b/drivers/base/firmware_class.c index 4497d263209f..89eb9de81145 100644 > --- a/drivers/base/firmware_class.c > +++ b/drivers/base/firmware_class.c > @@ -766,7 +770,7 @@ static ssize_t firmware_loading_store(struct device > *dev, dev_err(dev, "%s: unexpected value (%d)\n", __func__, loading); > /* fallthrough */ > case -1: > - fw_load_abort(fw_priv); > + fw_state_aborted(&fw_buf->fw_st); > break; > } > out: > > -------8<------------------------------------ > > Or should we fix up the ret code handling in __fw_state_wait_common()? I got this backwards, I blamed the wrong commit, it's the 5d47ec02c37e ("firmware: Correct handling of fw_state_wait() return value") in fact. It made the assumption that all errors returned from fw_state_wait_timeout() require calling the abort, while in fact abort should only be called if user mode helper didn't do anything (either it timed out or someone hit ^C). I'm leaning towards this: ------->8------------------------------------ diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c index 4497d263209f..ce142e6b2c72 100644 --- a/drivers/base/firmware_class.c +++ b/drivers/base/firmware_class.c @@ -1020,7 +1020,7 @@ static int _request_firmware_load(struct firmware_priv *fw_priv, } retval = fw_state_wait_timeout(&buf->fw_st, timeout); - if (retval < 0) { + if (retval == -ETIMEDOUT || retval == -ERESTARTSYS) { mutex_lock(&fw_lock); fw_load_abort(fw_priv); mutex_unlock(&fw_lock); -------8<------------------------------------ Unless advised otherwise I will submit this officially on Monday :)