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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 9AF2CC432C0 for ; Wed, 20 Nov 2019 22:10:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7B8CD20714 for ; Wed, 20 Nov 2019 22:10:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726202AbfKTWKv (ORCPT ); Wed, 20 Nov 2019 17:10:51 -0500 Received: from imap1.codethink.co.uk ([176.9.8.82]:36829 "EHLO imap1.codethink.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725819AbfKTWKv (ORCPT ); Wed, 20 Nov 2019 17:10:51 -0500 Received: from [167.98.27.226] (helo=xylophone) by imap1.codethink.co.uk with esmtpsa (Exim 4.84_2 #1 (Debian)) id 1iXYBR-0005dI-GG; Wed, 20 Nov 2019 22:10:45 +0000 Message-ID: Subject: Re: [Y2038] [PATCH 6/8] lp: fix sparc64 LPSETTIMEOUT ioctl From: Ben Hutchings To: Arnd Bergmann Cc: y2038 Mailman List , Greg Kroah-Hartman , "Gustavo A. R. Silva" , "linux-kernel@vger.kernel.org" , "# 3.4.x" , Bamvor Jian Zhang , Thomas Gleixner , Sudip Mukherjee Date: Wed, 20 Nov 2019 22:10:44 +0000 In-Reply-To: References: <20191108203435.112759-1-arnd@arndb.de> <20191108203435.112759-7-arnd@arndb.de> <41baf20a190039443cb2b82aea0c2a8ec872cfed.camel@codethink.co.uk> Organization: Codethink Ltd. Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.5-1.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2019-11-20 at 20:46 +0100, Arnd Bergmann wrote: > On Wed, Nov 20, 2019 at 8:27 PM Ben Hutchings > wrote: > > On Fri, 2019-11-08 at 21:34 +0100, Arnd Bergmann wrote: > > > The layout of struct timeval is different on sparc64 from > > > anything else, and the patch I did long ago failed to take > > > this into account. > > > > > > Change it now to handle sparc64 user space correctly again. > > > > > > Quite likely nobody cares about parallel ports on sparc64, > > > but there is no reason not to fix it. > > > > > > Cc: stable@vger.kernel.org > > > Fixes: 9a450484089d ("lp: support 64-bit time_t user space") > > > Signed-off-by: Arnd Bergmann > > > --- > > > drivers/char/lp.c | 4 ++++ > > > 1 file changed, 4 insertions(+) > > > > > > diff --git a/drivers/char/lp.c b/drivers/char/lp.c > > > index 7c9269e3477a..bd95aba1f9fe 100644 > > > --- a/drivers/char/lp.c > > > +++ b/drivers/char/lp.c > > > @@ -713,6 +713,10 @@ static int lp_set_timeout64(unsigned int minor, void __user *arg) > > > if (copy_from_user(karg, arg, sizeof(karg))) > > > return -EFAULT; > > > > > > + /* sparc64 suseconds_t is 32-bit only */ > > > + if (IS_ENABLED(CONFIG_SPARC64) && !in_compat_syscall()) > > > + karg[1] >>= 32; > > > + > > > return lp_set_timeout(minor, karg[0], karg[1]); > > > } > > > > > > > It seems like it would make way more sense to use __kernel_old_timeval. > > Right, that would work. I tried to keep the patch small here, changing > it to __kernel_old_timeval would require make it all more complicated > since it would still need to check some conditional to tell the difference > between sparc32 and sparc64. Right. > I think this patch (relative to the version I posted) would work the same: > > diff --git a/drivers/char/lp.c b/drivers/char/lp.c > index bd95aba1f9fe..86994421ee97 100644 > --- a/drivers/char/lp.c > +++ b/drivers/char/lp.c > @@ -713,13 +713,19 @@ static int lp_set_timeout64(unsigned int minor, > void __user *arg) > if (copy_from_user(karg, arg, sizeof(karg))) > return -EFAULT; > > - /* sparc64 suseconds_t is 32-bit only */ > - if (IS_ENABLED(CONFIG_SPARC64) && !in_compat_syscall()) > - karg[1] >>= 32; > - > return lp_set_timeout(minor, karg[0], karg[1]); > } > > +static int lp_set_timeout(unsigned int minor, void __user *arg) That function name is already used! Maybe this should be lp_set_timeout_old()? > +{ > + __kernel_old_timeval tv; > + > + if (copy_from_user(tv, arg, sizeof(karg))) > + return -EFAULT; > + > + return lp_set_timeout(minor, tv->tv_sec, tv->tv_usec); > +} > + > static long lp_ioctl(struct file *file, unsigned int cmd, > unsigned long arg) > { > @@ -730,11 +736,8 @@ static long lp_ioctl(struct file *file, unsigned int cmd, > mutex_lock(&lp_mutex); > switch (cmd) { > case LPSETTIMEOUT_OLD: > - if (BITS_PER_LONG == 32) { > - ret = lp_set_timeout32(minor, (void __user *)arg); > - break; > - } > - /* fall through - for 64-bit */ > + ret = lp_set_timeout(minor, (void __user *)arg); > + break; > case LPSETTIMEOUT_NEW: > ret = lp_set_timeout64(minor, (void __user *)arg); > break; > > Do you like that better? Yes. Aside from the duplicate function name, it looks correct and cleaner than the current version. > One difference here is the handling of > LPSETTIMEOUT_NEW on sparc64, which would continue to use > the 64/64 layout rather than the 64/32/pad layout, but that should > be ok, since sparc64 user space using ppdev (if any exists) > would use LPSETTIMEOUT_OLD, not LPSETTIMEOUT_NEW. Right, that's a little weird but appears to be consistent with "new" socket timestamps. > > Then you don't have to explicitly handle the sparc64 oddity. > > > > As it is, this still over-reads from user-space which might result in a > > spurious -EFAULT. > > I think you got this wrong: sparc64 like most architectures naturally > aligns 64-bit members, so 'struct timeval' still uses 16 bytes including > the four padding bytes at the end, it just has the nanoseconds in > a different position from all other big-endian architectures. Oh of course, yes. Ben. -- Ben Hutchings, Software Developer Codethink Ltd https://www.codethink.co.uk/ Dale House, 35 Dale Street Manchester, M1 2HF, United Kingdom