From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E42D8C47082 for ; Mon, 7 Jun 2021 07:57:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C1AE560238 for ; Mon, 7 Jun 2021 07:57:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230197AbhFGH7i (ORCPT ); Mon, 7 Jun 2021 03:59:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:56032 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229966AbhFGH7i (ORCPT ); Mon, 7 Jun 2021 03:59:38 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 89AF6611BE; Mon, 7 Jun 2021 07:57:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1623052667; bh=MIco8xVVHa5E67bXh4IpymS+jPfSoqyuBdI4aMtVwDw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mYvB+LGeiirFDPX94F0yzJCj02xe1h8yvT2RITid/224wYl0XNAkZcY9FDi8Beg7q VEj/srrbkacUDmY7yQZcm6dOTasMi0GIIM9PHu+j/fE5UEeiUgpxsSQYXgs6COzCh1 wngYYaKGm8/vZqJxMmRxUUPYUDJ2qjynI/0Wt8qRfesUf6C3xKpSLih0ViGRqkJgeU wS63N/QDWl9gF6/Ag7MWMsKmjR6rWLmpXW2HeiXxcMDDN47Vs2jbBcxANmKAQepYs1 iLZaNwTPUQiaBecGMzBIJRQc8+wzlWNHbkQTAAsToQKtZ0NgNCvuMR/GHHc5bHtArP le4g9znQ7hFnw== Received: from johan by xi.lan with local (Exim 4.94.2) (envelope-from ) id 1lqA8i-0004L1-Ky; Mon, 07 Jun 2021 09:57:40 +0200 Date: Mon, 7 Jun 2021 09:57:40 +0200 From: Johan Hovold To: Alan Stern Cc: Greg KH , USB mailing list , syzkaller-bugs@googlegroups.com Subject: Re: [PATCH] USB: core: Avoid WARNings for 0-length descriptor requests Message-ID: References: <20210603014354.GA1626048@rowland.harvard.edu> <0000000000007450cd05c3d3905d@google.com> <20210604161039.GI1676809@rowland.harvard.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210604161039.GI1676809@rowland.harvard.edu> Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Fri, Jun 04, 2021 at 12:10:39PM -0400, Alan Stern wrote: > The USB core has utility routines to retrieve various types of > descriptors. These routines will now provoke a WARN if they are asked > to retrieve 0 bytes (USB "receive" requests must not have zero > length), so avert this by checking the size argument at the start. > > Reported-and-tested-by: syzbot+7dbcd9ff34dc4ed45240@syzkaller.appspotmail.com > Signed-off-by: Alan Stern > CC: Johan Hovold > > --- > > > [as1962] > > > drivers/usb/core/message.c | 4 ++++ > 1 file changed, 4 insertions(+) > > Index: usb-devel/drivers/usb/core/message.c > =================================================================== > --- usb-devel.orig/drivers/usb/core/message.c > +++ usb-devel/drivers/usb/core/message.c > @@ -783,6 +783,8 @@ int usb_get_descriptor(struct usb_device > int i; > int result; > > + if (size <= 0) /* No point in asking for no data */ > + return -EINVAL; I'd put a newline after the sanity checks as Peter suggested too, but looks good otherwise so either way: Reviewed-by: Johan Hovold > memset(buf, 0, size); /* Make sure we parse really received data */ > > for (i = 0; i < 3; ++i) { > @@ -832,6 +834,8 @@ static int usb_get_string(struct usb_dev > int i; > int result; > > + if (size <= 0) /* No point in asking for no data */ > + return -EINVAL; > for (i = 0; i < 3; ++i) { > /* retry on length 0 or stall; some devices are flakey */ > result = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), Johan