Florian Westphal <fw@xxxxxxxxx> wrote:
> Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx> wrote:
> > On Sun, Feb 20, 2022 at 12:18:50PM +0100, Florian Westphal wrote:
> > > stateful objects can be updated from the control plane.
> > > The transaction logic allocates a temporary object for this purpose.
> > >
> > > This object has to be released via nft_obj_destroy, not kfree, since
> > > the ->init function was called and it can have side effects beyond
> > > memory allocation.
> > >
> > > Unlike normal NEWOBJ path, the objects module refcount isn't
> > > incremented, so add nft_newobj_destroy and use that.
> >
> > Probably this? .udata and .key is NULL for the update path so kfree
> > should be fine.
>
> Yes, that works too.
>
> We could also ...
>
> > - module_put(obj->ops->type->owner);
> > + /* nf_tables_updobj does not increment module refcount */
> > + if (!update)
> > + module_put(obj->ops->type->owner);
> > +
>
> Increment the refcount for update case as well to avoid the special
> case?
Untested:
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 3081c4399f10..49060f281342 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -6553,10 +6553,13 @@ static int nf_tables_updobj(const struct nft_ctx *ctx,
struct nft_trans *trans;
int err;
+ if (!try_module_get(type->owner))
+ return -ENOENT;
+
trans = nft_trans_alloc(ctx, NFT_MSG_NEWOBJ,
sizeof(struct nft_trans_obj));
if (!trans)
- return -ENOMEM;
+ goto err_trans;
newobj = nft_obj_init(ctx, type, attr);
if (IS_ERR(newobj)) {
@@ -6573,6 +6576,8 @@ static int nf_tables_updobj(const struct nft_ctx *ctx,
err_free_trans:
kfree(trans);
+err_trans:
+ module_put(type->owner);
return err;
}
@@ -8185,7 +8190,7 @@ static void nft_obj_commit_update(struct nft_trans *trans)
if (obj->ops->update)
obj->ops->update(obj, newobj);
- kfree(newobj);
+ nft_obj_destroy(&trans->ctx, newobj);
}
static void nft_commit_release(struct nft_trans *trans)
@@ -8976,7 +8981,7 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
break;
case NFT_MSG_NEWOBJ:
if (nft_trans_obj_update(trans)) {
- kfree(nft_trans_obj_newobj(trans));
+ nft_obj_destroy(&trans->ctx, nft_trans_obj_newobj(trans));
nft_trans_destroy(trans);
} else {
trans->ctx.table->use--;
