On 13 Oct 2023, at 8:56, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@xxxxxxxxxx>
>
> An XDR encoder is responsible for marshaling results, not releasing
> memory that was allocated by the upper layer. We have .op_release
> for that purpose.
>
> Move the release of the ld_owner.data string to op_release functions
> for LOCK and LOCKT.
>
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> ---
> fs/nfsd/nfs4proc.c | 2 ++
> fs/nfsd/nfs4state.c | 16 ++++++++++++++++
> fs/nfsd/nfs4xdr.c | 16 ++--------------
> fs/nfsd/xdr4.h | 17 +++++------------
> 4 files changed, 25 insertions(+), 26 deletions(-)
>
> Fix for kmemleak found during Bake-a-thon.
>
> I'm planning to insert this fix into nfsd-next just before the
> patches that clean up the lock_denied encoder.
>
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 60262fd27b15..f288039545e3 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -3210,6 +3210,7 @@ static const struct nfsd4_operation nfsd4_ops[] = {
> },
> [OP_LOCK] = {
> .op_func = nfsd4_lock,
> + .op_release = nfsd4_lock_release,
> .op_flags = OP_MODIFIES_SOMETHING |
> OP_NONTRIVIAL_ERROR_ENCODE,
> .op_name = "OP_LOCK",
> @@ -3218,6 +3219,7 @@ static const struct nfsd4_operation nfsd4_ops[] = {
> },
> [OP_LOCKT] = {
> .op_func = nfsd4_lockt,
> + .op_release = nfsd4_lockt_release,
> .op_flags = OP_NONTRIVIAL_ERROR_ENCODE,
> .op_name = "OP_LOCKT",
> .op_rsize_bop = nfsd4_lock_rsize,
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 07840ee721ef..305c353a416c 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -7773,6 +7773,14 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> return status;
> }
>
> +void nfsd4_lock_release(union nfsd4_op_u *u)
> +{
> + struct nfsd4_lock *lock = &u->lock;
> + struct nfsd4_lock_denied *deny = &lock->lk_denied;
> +
> + kfree(deny->ld_owner.data);
> +}
> +
> /*
> * The NFSv4 spec allows a client to do a LOCKT without holding an OPEN,
> * so we do a temporary open here just to get an open file to pass to
> @@ -7878,6 +7886,14 @@ nfsd4_lockt(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> return status;
> }
>
> +void nfsd4_lockt_release(union nfsd4_op_u *u)
> +{
> + struct nfsd4_lockt *lockt = &u->lockt;
> + struct nfsd4_lock_denied *deny = &lockt->lt_denied;
> +
> + kfree(deny->ld_owner.data);
> +}
> +
> __be32
> nfsd4_locku(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> union nfsd4_op_u *u)
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index dafb3a91235e..26e7bb6d32ab 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -3990,28 +3990,16 @@ nfsd4_encode_lock_denied(struct xdr_stream *xdr, struct nfsd4_lock_denied *ld)
> struct xdr_netobj *conf = &ld->ld_owner;
> __be32 *p;
>
> -again:
> p = xdr_reserve_space(xdr, 32 + XDR_LEN(conf->len));
> - if (!p) {
> - /*
> - * Don't fail to return the result just because we can't
> - * return the conflicting open:
> - */
> - if (conf->len) {
> - kfree(conf->data);
> - conf->len = 0;
> - conf->data = NULL;
> - goto again;
> - }
> + if (!p)
> return nfserr_resource;
Should we worry about removing this corner-case fix? I'm not sure I
understand it.. just wanted to bring it up. Here's what Bruce originally
said:
commit 8c7424cff6bd33459945646cfcbf6dc6c899ab24
Author: J. Bruce Fields <bfields@xxxxxxxxxxxx>
Date: Mon Mar 10 12:19:10 2014 -0400
nfsd4: don't try to encode conflicting owner if low on space
I ran into this corner case in testing: in theory clients can provide
state owners up to 1024 bytes long. In the sessions case there might be
a risk of this pushing us over the DRC slot size.
The conflicting owner isn't really that important, so let's humor a
client that provides a small maxresponsize_cached by allowing ourselves
to return without the conflicting owner instead of outright failing the
operation.
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
Ben
