Commit 58e3ce76 authored by Sishuai Gong's avatar Sishuai Gong Committed by Dominique Martinet
Browse files

9p/trans_fd: avoid sending req to a cancelled conn 



When a connection is cancelled by p9_conn_cancel(), all requests on it
should be cancelled---mark req->status as REQ_STATUS_ERROR. However,
because a race over m->err between p9_conn_cancel() and p9_fd_request(),
p9_fd_request might see the old value of m->err, think that the connection
is NOT cancelled, and then add new requests to this cancelled connection.

Fixing this issue by lock-protecting the check on m->err.

Signed-off-by: default avatarSishuai Gong <sishuai.system@gmail.com>
Message-ID: <AA2DB53B-DFC7-4B88-9515-E4C9AFA6435D@gmail.com>
Signed-off-by: default avatarDominique Martinet <asmadeus@codewreck.org>
Reviewed-by: default avatarChristian Schoenebeck <linux_oss@crudebyte.com>
parent 05d3ef8b

net/9p/trans_fd.c

+6 −2
Original line number Diff line number Diff line
@@ -671,10 +671,14 @@ static int p9_fd_request(struct p9_client *client, struct p9_req_t *req) 


	p9_debug(P9_DEBUG_TRANS, "mux %p task %p tcall %p id %d\n",

		 m, current, &req->tc, req->tc.id);

	if (m->err < 0)

		return m->err;



	spin_lock(&m->req_lock);



	if (m->err < 0) {

		spin_unlock(&m->req_lock);

		return m->err;

	}



	WRITE_ONCE(req->status, REQ_STATUS_UNSENT);

	list_add_tail(&req->req_list, &m->unsent_req_list);

	spin_unlock(&m->req_lock);