Re: [PATCH rdma-next 2/3] RDMA/core: Fix check of device in rdma_listen()

[Shay Drory <shayd@nvidia.com>]

On 4/22/2021 14:28, Jason Gunthorpe wrote:

> On Sun, Apr 18, 2021 at 04:55:53PM +0300, Leon Romanovsky wrote:
>> From: Shay Drory <shayd@nvidia.com>
>>
>> rdma_listen() checks if device already attached to rdma_id_priv,
>> based on the response the its decide to what to listen, however
>> this is different when the listeners are canceled.
>>
>> This leads to a mismatch between rdma_listen() and cma_cancel_operation(),
>> and causes to bellow wild-memory-access. Fix it by aligning rdma_listen()
>> according to the cma_cancel_operation().
> So this is happening because the error unwind in rdma_bind_addr() is
> taking the exit path and calling cma_release_dev()?
>
> This allows rdma_listen() to be called with a bogus device pointer
> which precipitates this UAF during destroy.
>
> However, I think rdma_bind_addr() should not allow the bogus device
> pointer to leak out at all, since the ULP could see it. It really is
> invalid to have it present no matter what.
>
> This would make cma_release_dev() and _cma_attach_to_dev()
> symmetrical - what do you think?
>
> diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
> index 2dc302a83014ae..91f6d968b46f65 100644
> --- a/drivers/infiniband/core/cma.c
> +++ b/drivers/infiniband/core/cma.c
> @@ -474,6 +474,7 @@ static void cma_release_dev(struct rdma_id_private *id_priv)
>   	list_del(&id_priv->list);
>   	cma_dev_put(id_priv->cma_dev);
>   	id_priv->cma_dev = NULL;
> +	id_priv->id.device = NULL;
>   	if (id_priv->id.route.addr.dev_addr.sgid_attr) {
>   		rdma_put_gid_attr(id_priv->id.route.addr.dev_addr.sgid_attr);
>   		id_priv->id.route.addr.dev_addr.sgid_attr = NULL;

I try that. this will break restrack_del() since restrack_del() is using id_priv->id.device
and is being called before restrack_del():
_destroy_id <https://elixir.bootlin.com/linux/v5.11/C/ident/_destroy_id>() {
if (id_priv 
<https://elixir.bootlin.com/linux/v5.11/C/ident/id_priv>->cma_dev 
<https://elixir.bootlin.com/linux/v5.11/C/ident/cma_dev>) 
cma_release_dev 
<https://elixir.bootlin.com/linux/v5.11/C/ident/cma_release_dev>(id_priv 
<https://elixir.bootlin.com/linux/v5.11/C/ident/id_priv>); ... 
rdma_restrack_del 
<https://elixir.bootlin.com/linux/v5.11/C/ident/rdma_restrack_del>(&id_priv 
<https://elixir.bootlin.com/linux/v5.11/C/ident/id_priv>->res); }