Re: [PATCH for-next] RDMA/rtrs-clt: destroy sysfs after removing session from active list

[Jason Gunthorpe <jgg@nvidia.com>]

On Mon, Apr 12, 2021 at 10:40:02AM +0200, Gioh Kim wrote:
> A session can be removed dynamically by sysfs interface "remove_path"
> that eventually calls rtrs_clt_remove_path_from_sysfs function.
> The current rtrs_clt_remove_path_from_sysfs first removes the sysfs
> interfaces and frees sess->stats object. Second it removes the session
> from the active list.
> 
> Therefore some functions could access non-connected session and
> access the freed sess->stats object even-if they check the session
> status before accessing the session.
> For instance rtrs_clt_request and get_next_path_min_inflight
> check the session status and try to send IO to the session.
> The session status could be changed when they are trying to send IO
> but they could not catch the change and update the statistics information
> in sess->stats object, and generate use-after-free problem.
> (see: "RDMA/rtrs-clt: Check state of the rtrs_clt_sess before reading
> its stats")
> 
> This patch changes the rtrs_clt_remove_path_from_sysfs to remove
> the session from the active session list and then destroy the sysfs
> interfaces.
> 
> Each function still should check the session status because closing
> or error recovery paths can change the status.
> 
> Fixes: 6a98d71daea1 ("RDMA/rtrs: client: main functionality")
> Signed-off-by: Gioh Kim <gi-oh.kim@ionos.com>
> Reviewed-by: Jack Wang <jinpu.wang@ionos.com>
> ---
>  drivers/infiniband/ulp/rtrs/rtrs-clt.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Applied to for-next, thanks

Jason