Re: [PATCH] cifs: fix race between compound_send_recv() and the demultiplex thread

[Pavel Shilovsky <piastryyy@gmail.com>]

ср, 13 нояб. 2019 г. в 22:17, Ronnie Sahlberg <lsahlber@redhat.com>:
>
> There is a race where the open() may be interrupted between when we receive the reply
> but before we have invoked the callback in which case we never end up calling
> handle_cancelled_mid() and thus leak an open handle on the server.
>
> Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
> ---
>  fs/cifs/connect.c   | 1 -
>  fs/cifs/transport.c | 2 +-
>  2 files changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index ccaa8bad336f..802604a7e692 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -1223,7 +1223,6 @@ cifs_demultiplex_thread(void *p)
>                         if (mids[i] != NULL) {
>                                 mids[i]->resp_buf_size = server->pdu_size;
>                                 if ((mids[i]->mid_flags & MID_WAIT_CANCELLED) &&
> -                                   mids[i]->mid_state == MID_RESPONSE_RECEIVED &&
>                                     server->ops->handle_cancelled_mid)
>                                         server->ops->handle_cancelled_mid(
>                                                         mids[i]->resp_buf,
> diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
> index ca3de62688d6..0f219f7653f3 100644
> --- a/fs/cifs/transport.c
> +++ b/fs/cifs/transport.c
> @@ -1119,7 +1119,7 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
>                                  midQ[i]->mid, le16_to_cpu(midQ[i]->command));
>                         send_cancel(server, &rqst[i], midQ[i]);
>                         spin_lock(&GlobalMid_Lock);
> -                       if (midQ[i]->mid_state == MID_REQUEST_SUBMITTED) {
> +                       if (is_interrupt_error(rc)) {
>                                 midQ[i]->mid_flags |= MID_WAIT_CANCELLED;
>                                 midQ[i]->callback = cifs_cancelled_callback;
>                                 cancelled_mid[i] = true;
> --
> 2.13.6
>

It doesn't seem that RC may be anything other than -ERESTARTSYS but
is_interrupt_error() should work.

Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

--
Best regards,
Pavel Shilovsky