From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Teigland Date: Tue, 11 Oct 2022 10:20:31 -0500 Subject: [Cluster-devel] [PATCH v2][next] dlm: Replace one-element array with flexible-array member In-Reply-To: <202210101534.BA51029@keescook> References: <378C6BDE-0A68-4938-86CD-495BD5F35BE6@chromium.org> <202210082044.51106145BD@keescook> <20221010210039.GA30273@redhat.com> <202210101534.BA51029@keescook> Message-ID: <20221011152031.GA11089@redhat.com> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Mon, Oct 10, 2022 at 03:35:24PM -0700, Kees Cook wrote: > On Mon, Oct 10, 2022 at 04:00:39PM -0500, David Teigland wrote: > > On Sat, Oct 08, 2022 at 09:03:28PM -0700, Kees Cook wrote: > > > On Sun, Oct 09, 2022 at 03:05:17PM +1300, Paulo Miguel Almeida wrote: > > > > On Sat, Oct 08, 2022 at 05:18:35PM -0700, Kees Cook wrote: > > > > > This is allocating 1 more byte than before, since the struct size didn't change. But this has always allocated too much space, due to the struct padding. For a "no binary changes" patch, the above "+ 1" needs to be left off. > > > > > > > > That's true. I agree that leaving "+ 1" would work and produce a > > > > no-binary-changes patch due to the existing padding that the structure > > > > has. OTOH, I thought that relying on that space could bite us in the > > > > future if anyone tweaks the struct again...so my reaction was to ensure > > > > that the NUL-terminator space was always guaranteed to be there. > > > > Hence, the change on c693 (objdump above). > > > > > > > > What do you think? Should we keep or leave the above > > > > "+ 1" after the rationale above? > > > > > > I think it depends on what's expected from this allocation. Christine or > > > David, can you speak to this? > > > > Hi, thanks for picking through that. Most likely the intention was to > > allow up to 64 (DLM_LOCKSPACE_LEN) character names, and then use the > > ls_name[1] for the terminating byte. I'd be happy to take the patch > > Should this just use: > > char ls_name[DLM_LOCKSPACE_LEN + 1]; > > instead, or is the byte savings worth keeping it dynamically sized? Yes, I think that's the best option. Dave