From: Sishuai Gong Date: Tue, 8 Aug 2023 16:44:31 +0000 (-0400) Subject: 9p/trans_fd: avoid sending req to a cancelled conn X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=58e3ce767307130e911408c75f054d6a6673c8a3;p=linux.git 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: Sishuai Gong Message-ID: Signed-off-by: Dominique Martinet Reviewed-by: Christian Schoenebeck --- diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index c4015f30f9fa7..f226953577b26 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -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);