On Tue, Feb 4, 2025 at 4:59 PM Richard Guo <guofengli...@gmail.com> wrote: > On Thu, Nov 7, 2024 at 7:07 PM Tender Wang <tndrw...@gmail.com> wrote: > > While learning gist index insert codes, I find a little issue with > > BufferGetLSNAtomic(). > > At first, it wants to get bufHdr by accessing the buffer descriptor array, > > as below: > > > > BufferDesc *bufHdr = GetBufferDescriptor(buffer - 1); > > > > However, it doesn't check whether the passed buffer is a local or shared > > buffer. > > If the buffer is local, then buffer < 0; it will be cast to uint32 when > > passed to GetBufferDescriptor(). > > This may be unsafe, although no someone reports the problem. > > > > I tweak a few codes; see the attached patch. > > Any thoughts? > > LGTM. When considering a local buffer, the GetBufferDescriptor() call > in BufferGetLSNAtomic() would be retrieving a shared buffer with a bad > buffer ID. Since the code checks whether the buffer is shared before > using the retrieved BufferDesc, this issue did not lead to any > malfunction. Nonetheless this seems like trouble waiting to happen.
I plan to push this shortly. This is arguably a bug, but it hasn't caused any real issues, and nobody has complained about it until now, so I don't think it needs to be back-patched. Any thoughts? Thanks Richard
