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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E6D67C433EF for ; Fri, 7 Jan 2022 02:37:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345487AbiAGCh7 (ORCPT ); Thu, 6 Jan 2022 21:37:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54320 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345477AbiAGCh6 (ORCPT ); Thu, 6 Jan 2022 21:37:58 -0500 Received: from mail-yb1-xb2b.google.com (mail-yb1-xb2b.google.com [IPv6:2607:f8b0:4864:20::b2b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E7D59C061245; Thu, 6 Jan 2022 18:37:57 -0800 (PST) Received: by mail-yb1-xb2b.google.com with SMTP id p5so5578050ybd.13; Thu, 06 Jan 2022 18:37:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=wypQ1B8KjY0Soft/ehKx+C81O0i047qr+0bKMSezlyE=; b=ZSX0AjZWzsMncHFPoSX4wVtu1ShqU4f2e74sB1+uyHDZK78jKKLH1ISljHHZRTTwTc 25HA7V46+Qj8snps1JcRhzt6PKLKnLnCi7Zlw0CdDNrAIXZGPudIYybqRL0bls3RfqHq /Kzegt1a3hUCQ0P5NIENkt5M6O0Vv2ftw4l3GbPZOQ5a0RVu68x8l/NHHNuHJ4Q3if+7 s1fMTHNiLdU4QtQ8bhRYKSvLioICBuQIKjJvkRWY35gi/T8u6sUd7LIlqIyQOXGYj+Pb Nd1icj15dEzjRsVPJuJGHxwK3Y0gmsVtNYiG9ecBfV7J7svkunGnj728nIrXZvIe2FvT 2ZhQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=wypQ1B8KjY0Soft/ehKx+C81O0i047qr+0bKMSezlyE=; b=4ZWuj0lO6z835oxY9ew72p3n4KD+kxbzoEZJVH84o7hy1jSFZwJkU+Icrprz4xr5xc oN6sBeGvq/a6uDQVHqO0Q8uEq6XdW/3NKylH1cH3VpiQzp2hAjuDekPG86QgDNFmwrti 0ZADNBD2ibJJ6CLBaQ8Y87n9aN03gJ95QUl4KMWkgtA2sddfe+oxZHAnjFhLbM5QZ/OT Uu+mU+/k7NhafASt3c5YVam2x3kdA3rS44AmaqEx0qAC9bGgSMO01sl/YdRkbtu8Nasc RT4tQ3baP7bWTSU/5mnU884Rl7mT9+Fu/pE6rZPHjqALWXgrJPasd94M7liorbNVSWXQ R0eA== X-Gm-Message-State: AOAM533xZvD2u3hcmdrpnAWQqjiHvFQBtexqgn954iLTuvqYTSc5X0VH eXu8f6PqgV2kqbyWC0sJcmvOwcVlsUGmfyyKJuE= X-Google-Smtp-Source: ABdhPJybXPBDx44szVsqBODATOKTyxDlPIW2nev+koeFPjJaw5evJtOELlJDPHAZrh6W02kLH7gbmQMEad0DAT9uxNs= X-Received: by 2002:a25:8a:: with SMTP id 132mr63689371yba.738.1641523077116; Thu, 06 Jan 2022 18:37:57 -0800 (PST) MIME-Version: 1.0 References: <20220105040439.3182-1-jj251510319013@gmail.com> In-Reply-To: From: =?UTF-8?B?6Zmz5YGJ6YqY?= Date: Fri, 7 Jan 2022 10:37:19 +0800 Message-ID: Subject: Re: [PATCH] usb: gadget: function: Fix returning incorrect PNP string To: Greg KH Cc: linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, balbi@kernel.org, =?UTF-8?Q?Maciej_=C5=BBenczykowski?= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Greg KH =E6=96=BC 2022=E5=B9=B41=E6=9C=886=E6= =97=A5 =E9=80=B1=E5=9B=9B =E4=B8=8B=E5=8D=8810:35=E5=AF=AB=E9=81=93=EF=BC= =9A > > On Wed, Jan 05, 2022 at 12:04:39PM +0800, Wei Ming Chen wrote: > > There will be 2 leading bytes indicating the total length of > > the PNP string, so I think we should add value by 2, otherwise > > the PNP string copied to user will not contain the last 2 bytes > > > > Signed-off-by: Wei Ming Chen > > --- > > drivers/usb/gadget/function/f_printer.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadg= et/function/f_printer.c > > index abec5c58f525..3fb00fd0b5ee 100644 > > --- a/drivers/usb/gadget/function/f_printer.c > > +++ b/drivers/usb/gadget/function/f_printer.c > > @@ -1005,9 +1005,11 @@ static int printer_func_setup(struct usb_functio= n *f, > > break; > > } > > value =3D strlen(dev->pnp_string); > > + memcpy(buf + 2, dev->pnp_string, value); > > + > > + value +=3D 2; > > buf[0] =3D (value >> 8) & 0xFF; > > buf[1] =3D value & 0xFF; > > - memcpy(buf + 2, dev->pnp_string, value); > > DBG(dev, "1284 PNP String: %x %s\n", value, > > dev->pnp_string); > > break; > > -- > > 2.25.1 > > > > Are you sure this is correct? > > How is this related to this recent thread: > https://lore.kernel.org/all/CAKjGFBUdjXcZoVV4jdrgTz4rKThTfZAK4Cqr= eKmBZ4KHE+K1GA@mail.gmail.com/#t > > your change is different from what is proposed there, why? I didn=E2=80=99t notice this thread before I send this patch, I think the concept of my change is similar to Volodymyr Lisivka=E2=80=99s change, he/s= he introduced a separate variable for the PNP string length, I think it may be clearer and more readable than just =E2=80=9Cvalue +=3D 2=E2=80=9D Another thing that I am not too sure whether I am correct is this line of c= ode DBG(dev, "1284 PNP String: %x %s\n", value, dev->pnp_string); What Volodymyr Lisivka changed is like this DBG(dev, "1284 PNP String: %x %s\n", pnp_length, dev->pnp_string); In my change, =E2=80=9Cvalue=E2=80=9D equals to =E2=80=9Cpnp_length + 2=E2= =80=9D in Volodymyr Lisivka=E2=80=99s change, and I think we should print =E2=80=9Cthe PNP stri= ng length + 2=E2=80=9D instead of =E2=80=9Cthe PNP string length=E2=80=9D? > > thanks, > > greg k-h thanks, Wei Ming Chen