From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Teigland Date: Mon, 10 Oct 2022 16:00:39 -0500 Subject: [Cluster-devel] [PATCH v2][next] dlm: Replace one-element array with flexible-array member In-Reply-To: <202210082044.51106145BD@keescook> References: <378C6BDE-0A68-4938-86CD-495BD5F35BE6@chromium.org> <202210082044.51106145BD@keescook> Message-ID: <20221010210039.GA30273@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 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 replacing the one-element name. Or, if you'd like to drop it, then we'll eliminate it along with a cleanup of name/namelen more broadly. Dave