On Jan 31, 2023, at 8:36 AM, Jeff Layton [off-list ref] wrote:

On Sat, 2023-01-28 at 20:44 -0800, Dai Ngo wrote:

quoted

When nfsd4_copy fails to allocate memory for async_copy->cp_src, or
nfs4_init_copy_state fails, it calls cleanup_async_copy to do the
cleanup for the async_copy which causes page fault since async_copy
is not yet initialized.

This patch rearranges the order of initializing the fields in
async_copy and adds checks in cleanup_async_copy to skip un-initialized
fields.

Fixes: ce0887ac96d3 ("NFSD add nfs4 inter ssc to nfsd4_copy")
Fixes: 87689df69491 ("NFSD: Shrink size of struct nfsd4_copy")
Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
fs/nfsd/nfs4proc.c  | 12 ++++++++----
fs/nfsd/nfs4state.c |  5 +++--
2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 57f791899de3..0754b38d3a43 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c

@@ -1687,9 +1687,12 @@ static void cleanup_async_copy(struct nfsd4_copy *copy)

{
	nfs4_free_copy_state(copy);
	release_copy_files(copy);
-	spin_lock(&copy->cp_clp->async_lock);
-	list_del(&copy->copies);
-	spin_unlock(&copy->cp_clp->async_lock);
+	if (copy->cp_clp) {
+		spin_lock(&copy->cp_clp->async_lock);
+		if (!list_empty(&copy->copies))
+			list_del(&copy->copies);

Can we make this a list_del_init? If cleanup_async_copy were called on
this twice, then the second time could end up corrupting the
async_copies list. The cost difference is negligible here.

I noticed this yesterday and made the change in my tree.

quoted

+		spin_unlock(&copy->cp_clp->async_lock);
+	}
	nfs4_put_copy(copy);
}

@@ -1786,12 +1789,13 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,

		async_copy = kzalloc(sizeof(struct nfsd4_copy), GFP_KERNEL);
		if (!async_copy)
			goto out_err;
+		INIT_LIST_HEAD(&async_copy->copies);
+		refcount_set(&async_copy->refcount, 1);
		async_copy->cp_src = kmalloc(sizeof(*async_copy->cp_src), GFP_KERNEL);
		if (!async_copy->cp_src)
			goto out_err;
		if (!nfs4_init_copy_state(nn, copy))
			goto out_err;
-		refcount_set(&async_copy->refcount, 1);
		memcpy(&copy->cp_res.cb_stateid, &copy->cp_stateid.cs_stid,
			sizeof(copy->cp_res.cb_stateid));
		dup_copy_fields(copy, async_copy);

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index ace02fd0d590..c39e43742dd6 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c

@@ -975,7 +975,6 @@ static int nfs4_init_cp_state(struct nfsd_net *nn, copy_stateid_t *stid,

	stid->cs_stid.si_opaque.so_clid.cl_boot = (u32)nn->boot_time;
	stid->cs_stid.si_opaque.so_clid.cl_id = nn->s2s_cp_cl_id;
-	stid->cs_type = cs_type;

	idr_preload(GFP_KERNEL);
	spin_lock(&nn->s2s_cp_lock);

@@ -986,6 +985,7 @@ static int nfs4_init_cp_state(struct nfsd_net *nn, copy_stateid_t *stid,

	idr_preload_end();
	if (new_id < 0)
		return 0;
+	stid->cs_type = cs_type;
	return 1;
}

@@ -1019,7 +1019,8 @@ void nfs4_free_copy_state(struct nfsd4_copy *copy)

{
	struct nfsd_net *nn;

-	WARN_ON_ONCE(copy->cp_stateid.cs_type != NFS4_COPY_STID);
+	if (copy->cp_stateid.cs_type != NFS4_COPY_STID)
+		return;

It's probably fine to keep the WARN_ON_ONCE here. You're testing the
condition anyway so you can do:

   if (WARN_ON_ONCE(copy->cp_stateid.cs_type != NFS4_COPY_STID))

Six of one...

I'm OK leaving the WARN out, it doesn't seem high value to me.

quoted

	nn = net_generic(copy->cp_clp->net, nfsd_net_id);
	spin_lock(&nn->s2s_cp_lock);
	idr_remove(&nn->s2s_cp_stateids,

-- 
Jeff Layton [off-list ref]

--
Chuck Lever