From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ipmail06.adl6.internode.on.net ([150.101.137.145]:49466 "EHLO ipmail06.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753044AbdLFA1q (ORCPT ); Tue, 5 Dec 2017 19:27:46 -0500 Date: Wed, 6 Dec 2017 11:27:43 +1100 From: Dave Chinner Subject: Re: [xfsprogs PATCH v2 1/3] xfs_io: fix compiler warnings in getfsmap code Message-ID: <20171206002743.GC5858@dastard> References: <20171205235651.17102-1-ross.zwisler@linux.intel.com> <20171205235651.17102-2-ross.zwisler@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20171205235651.17102-2-ross.zwisler@linux.intel.com> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Ross Zwisler Cc: linux-xfs , linux-nvdimm , fstests , Jan Kara , Dan Williams , "Darrick J . Wong" On Tue, Dec 05, 2017 at 04:56:49PM -0700, Ross Zwisler wrote: > I recently upgraded my compiler from > gcc (GCC) 6.4.1 20170727 (Red Hat 6.4.1-1) > to > gcc (GCC) 7.2.1 20170915 (Red Hat 7.2.1-2) > and started getting a bunch of compiler warnings in io/fsmap.c: > > fsmap.c: In function ‘fsmap_f’: > fsmap.c:228:40: warning: ‘%lld’ directive output may be truncated writing > between 1 and 17 bytes into a region of size between 12 and 28 > [-Wformat-truncation=] > snprintf(bbuf, sizeof(bbuf), "[%lld..%lld]:", > ^~~~ > fsmap.c:228:32: note: directive argument in the range [0, 36028797018963967] > snprintf(bbuf, sizeof(bbuf), "[%lld..%lld]:", > ^~~~~~~~~~~~~~~ > fsmap.c:228:3: note: ‘snprintf’ output between 8 and 40 bytes into a > destination of size 32 > snprintf(bbuf, sizeof(bbuf), "[%lld..%lld]:", > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > (long long)BTOBBT(p->fmr_physical), > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > (long long)BTOBBT(p->fmr_physical + p->fmr_length - 1)); > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > The issue is that 'bbuf' is only defined to be 32 characters wide, but each > signed long long can potentially print as many as 19 characters > (9223372036854775807 is the max value). The format we're using for bbuf is > "[%lld..%lld]:" which has 2 signed long longs plus 6 other characters > "[..]:\0", which means it's possible we'll print up to 44 characters, > overflowing our 32 char buffer. > > Fix this by bumping all the buffer sizes in dump_map_verbose() to 64 > characters. > > Signed-off-by: Ross Zwisler > Cc: Darrick J. Wong > Fixes: 3fcab549a234 ("xfs_io: support the new getfsmap ioctl") FYI, I posted a fix for this weeks ago. I think Eric has already picked it up, but it hasn't been pushed out into the for-next branch yet. Cheers, Dave. -- Dave Chinner david@fromorbit.com