Re: [PATCH 00/38] lockd: Convert NLMv3 server-side procedures to xdrgen

[Jeff Layton <jlayton@kernel.org>]

On Thu, 2026-05-14 at 13:53 -0400, Chuck Lever wrote:
> On Thu, May 14, 2026, at 12:52 PM, Jeff Layton wrote:
> 
> > I got a sketchy review from Gemini that I had Claude validate that
> > looks valid. You may want to add the memset() it recommends:
> > 
> > --------------8<---------------
> > 
> >   Analysis complete. The previous review (against b201ce7af2a2
> > FREE_ALL) identified the right underlying bug but attributed it to the
> > wrong commit. Here's the corrected analysis:
> > 
> >   Correct commit: 3de744ee4e45 — "lockd: Use xdrgen XDR functions for
> > the NLMv4 TEST procedure"
> > 
> >   The regression: nlm4svc_lookup_file() (introduced in this commit)
> > copies only fh.len bytes of the file handle without zeroing the
> > remainder. Combined with .pc_argzero = 0 removing the
> >   defensive memset of the argument buffer, bytes beyond fh.len in lock-
> > > fh.data contain stale data from previous RPC calls. file_hash() in
> > fs/lockd/svcsubs.c reads a fixed 32 bytes (NFS2_FHSIZE)
> >    regardless of actual handle length, so for handles shorter than 32
> > bytes the hash is non-deterministic — the same file handle can hash to
> > different buckets on different calls, causing lock
> >   state lookup failures.
> 
> This appears to be a regression introduced by the (previous) NLMv4
> series, and does not affect the current NLMv3 xdrgen conversion.
> 
> I can post a fix for this later today. Note that memset() was
> removed as part of the xdrgen conversion because it zeroes much
> more memory than actually needs to be initialized.
> 


I couldn't quite tell. It almost sounded like the change in the
original patch was safe, but this series removed some protections that
made it safe to skip the zeroing? In any case it sounds like a real bug
that we should probably fix, though it can be done in a later patch.

The series itself seems mostly mechanical. You can add:

Reviewed-by: Jeff Layton <jlayton@kernel.org>