From: Tomas Bortoli <tomasbortoli@xxxxxxxxx> [ Upstream commit 9f476d7c540cb57556d3cc7e78704e6cd5100f5f ] It may be possible to run p9_fd_cancel() with a deleted req->req_list and incur in a double del. To fix hold the client->lock while changing the status, so the other threads will be synchronized. Link: http://lkml.kernel.org/r/20180723184253.6682-1-tomasbortoli@xxxxxxxxx Signed-off-by: Tomas Bortoli <tomasbortoli@xxxxxxxxx> Reported-by: syzbot+735d926e9d1317c3310c@xxxxxxxxxxxxxxxxxxxxxxxxx To: Eric Van Hensbergen <ericvh@xxxxxxxxx> To: Ron Minnich <rminnich@xxxxxxxxxx> To: Latchesar Ionkov <lucho@xxxxxxxxxx> Cc: Yiwen Jiang <jiangyiwen@xxxxxxxxx> Cc: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Dominique Martinet <dominique.martinet@xxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> --- net/9p/trans_fd.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index 588bf88c3305..f9f96d50d96d 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -197,15 +197,14 @@ static void p9_mux_poll_stop(struct p9_conn *m) static void p9_conn_cancel(struct p9_conn *m, int err) { struct p9_req_t *req, *rtmp; - unsigned long flags; LIST_HEAD(cancel_list); p9_debug(P9_DEBUG_ERROR, "mux %p err %d\n", m, err); - spin_lock_irqsave(&m->client->lock, flags); + spin_lock(&m->client->lock); if (m->err) { - spin_unlock_irqrestore(&m->client->lock, flags); + spin_unlock(&m->client->lock); return; } @@ -217,7 +216,6 @@ static void p9_conn_cancel(struct p9_conn *m, int err) list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) { list_move(&req->req_list, &cancel_list); } - spin_unlock_irqrestore(&m->client->lock, flags); list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) { p9_debug(P9_DEBUG_ERROR, "call back req %p\n", req); @@ -226,6 +224,7 @@ static void p9_conn_cancel(struct p9_conn *m, int err) req->t_err = err; p9_client_cb(m->client, req, REQ_STATUS_ERROR); } + spin_unlock(&m->client->lock); } static __poll_t @@ -373,8 +372,9 @@ static void p9_read_work(struct work_struct *work) if (m->req->status != REQ_STATUS_ERROR) status = REQ_STATUS_RCVD; list_del(&m->req->req_list); - spin_unlock(&m->client->lock); + /* update req->status while holding client->lock */ p9_client_cb(m->client, m->req, status); + spin_unlock(&m->client->lock); m->rc.sdata = NULL; m->rc.offset = 0; m->rc.capacity = 0; -- 2.17.1
