[PATCH 6.12.y 2/2] nfsd: release layout stid on setlease failure

commit 30d55c8aabb261bc3f427d6b9aae7ef6206063f9 upstream.

nfs4_alloc_stid() publishes the new stid into cl->cl_stateids via
idr_alloc_cyclic() under cl_lock before returning to
nfsd4_alloc_layout_stateid(). When nfsd4_layout_setlease() then
fails, the error path frees the layout stateid directly with
kmem_cache_free() without ever calling idr_remove(), leaving the
IDR slot pointing at freed slab memory. Any subsequent IDR walker
(states_show, client teardown) dereferences the dangling pointer.

The correct teardown for an IDR-published stid is nfs4_put_stid(),
which removes the IDR slot under cl_lock, dispatches sc_free
(nfsd4_free_layout_stateid) to release ls->ls_file via
nfsd4_close_layout(), and drops the nfs4_file reference in its
tail.

Replace the manual nfsd_file_put + put_nfs4_file + kmem_cache_free
cleanup with a single nfs4_put_stid(stp).

Fixes: c5c707f96fc9 ("nfsd: implement pNFS layout recalls")
Cc: [email protected]
Signed-off-by: Chris Mason <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
Signed-off-by: Chuck Lever <[email protected]>
Signed-off-by: Chuck Lever <[email protected]>
[ cel: no ls_fence_work in 6.12.y; dropped INIT_DELAYED_WORK hunk ]
Signed-off-by: Chuck Lever <[email protected]>
---
 fs/nfsd/nfs4layouts.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c
index fc5e82eddaa1..c08bc2d0d377 100644
--- a/fs/nfsd/nfs4layouts.c
+++ b/fs/nfsd/nfs4layouts.c
@@ -256,9 +256,7 @@ nfsd4_alloc_layout_stateid(struct nfsd4_compound_state *cstate,
 	BUG_ON(!ls->ls_file);
 
 	if (nfsd4_layout_setlease(ls)) {
-		nfsd_file_put(ls->ls_file);
-		put_nfs4_file(fp);
-		kmem_cache_free(nfs4_layout_stateid_cache, ls);
+		nfs4_put_stid(stp);
 		return NULL;
 	}
 
-- 
2.54.0