4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Tomas Bortoli tomasbortoli@gmail.com
[ 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@gmail.com Signed-off-by: Tomas Bortoli tomasbortoli@gmail.com Reported-by: syzbot+735d926e9d1317c3310c@syzkaller.appspotmail.com To: Eric Van Hensbergen ericvh@gmail.com To: Ron Minnich rminnich@sandia.gov To: Latchesar Ionkov lucho@ionkov.net Cc: Yiwen Jiang jiangyiwen@huwei.com Cc: David S. Miller davem@davemloft.net Signed-off-by: Dominique Martinet dominique.martinet@cea.fr Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/9p/trans_fd.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
--- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -195,15 +195,14 @@ static void p9_mux_poll_stop(struct p9_c 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; }
@@ -215,7 +214,6 @@ static void p9_conn_cancel(struct p9_con 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); @@ -224,6 +222,7 @@ static void p9_conn_cancel(struct p9_con req->t_err = err; p9_client_cb(m->client, req, REQ_STATUS_ERROR); } + spin_unlock(&m->client->lock); }
static int @@ -379,8 +378,9 @@ static void p9_read_work(struct work_str 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;