From: Dominique Martinet <asmadeus@xxxxxxxxxxxxx> commit 296ab4a813841ba1d5f40b03190fd1bd8f25aab0 upstream. Shamelessly copying the explanation from Tetsuo Handa's suggested patch[1] (slightly reworded): syzbot is reporting inconsistent lock state in p9_req_put()[2], for p9_tag_remove() from p9_req_put() from IRQ context is using spin_lock_irqsave() on "struct p9_client"->lock but trans_fd (not from IRQ context) is using spin_lock(). Since the locks actually protect different things in client.c and in trans_fd.c, just replace trans_fd.c's lock by a new one specific to the transport (client.c's protect the idr for fid/tag allocations, while trans_fd.c's protects its own req list and request status field that acts as the transport's state machine) Link: https://lore.kernel.org/r/20220904112928.1308799-1-asmadeus@xxxxxxxxxxxxx Link: https://lkml.kernel.org/r/2470e028-9b05-2013-7198-1fdad071d999@xxxxxxxxxxxxxxxxxxx [1] Link: https://syzkaller.appspot.com/bug?extid=2f20b523930c32c160cc [2] Reported-by: syzbot <syzbot+2f20b523930c32c160cc@xxxxxxxxxxxxxxxxxxxxxxxxx> Reported-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Reviewed-by: Christian Schoenebeck <linux_oss@xxxxxxxxxxxxx> Signed-off-by: Dominique Martinet <asmadeus@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/9p/trans_fd.c | 41 +++++++++++++++++++++++++---------------- 1 file changed, 25 insertions(+), 16 deletions(-) --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -93,6 +93,7 @@ struct p9_poll_wait { * @mux_list: list link for mux to manage multiple connections (?) * @client: reference to client instance for this connection * @err: error state + * @req_lock: lock protecting req_list and requests statuses * @req_list: accounting for requests which have been sent * @unsent_req_list: accounting for requests that haven't been sent * @rreq: read request @@ -116,6 +117,7 @@ struct p9_conn { struct list_head mux_list; struct p9_client *client; int err; + spinlock_t req_lock; struct list_head req_list; struct list_head unsent_req_list; struct p9_req_t *rreq; @@ -191,10 +193,10 @@ static void p9_conn_cancel(struct p9_con p9_debug(P9_DEBUG_ERROR, "mux %p err %d\n", m, err); - spin_lock(&m->client->lock); + spin_lock(&m->req_lock); if (m->err) { - spin_unlock(&m->client->lock); + spin_unlock(&m->req_lock); return; } @@ -207,7 +209,7 @@ static void p9_conn_cancel(struct p9_con list_move(&req->req_list, &cancel_list); } - spin_unlock(&m->client->lock); + spin_unlock(&m->req_lock); list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) { p9_debug(P9_DEBUG_ERROR, "call back req %p\n", req); @@ -362,7 +364,7 @@ static void p9_read_work(struct work_str if ((m->rreq) && (m->rc.offset == m->rc.capacity)) { p9_debug(P9_DEBUG_TRANS, "got new packet\n"); m->rreq->rc.size = m->rc.offset; - spin_lock(&m->client->lock); + spin_lock(&m->req_lock); if (m->rreq->status == REQ_STATUS_SENT) { list_del(&m->rreq->req_list); p9_client_cb(m->client, m->rreq, REQ_STATUS_RCVD); @@ -371,14 +373,14 @@ static void p9_read_work(struct work_str p9_debug(P9_DEBUG_TRANS, "Ignore replies associated with a cancelled request\n"); } else { - spin_unlock(&m->client->lock); + spin_unlock(&m->req_lock); p9_debug(P9_DEBUG_ERROR, "Request tag %d errored out while we were reading the reply\n", m->rc.tag); err = -EIO; goto error; } - spin_unlock(&m->client->lock); + spin_unlock(&m->req_lock); m->rc.sdata = NULL; m->rc.offset = 0; m->rc.capacity = 0; @@ -456,10 +458,10 @@ static void p9_write_work(struct work_st } if (!m->wsize) { - spin_lock(&m->client->lock); + spin_lock(&m->req_lock); if (list_empty(&m->unsent_req_list)) { clear_bit(Wworksched, &m->wsched); - spin_unlock(&m->client->lock); + spin_unlock(&m->req_lock); return; } @@ -474,7 +476,7 @@ static void p9_write_work(struct work_st m->wpos = 0; p9_req_get(req); m->wreq = req; - spin_unlock(&m->client->lock); + spin_unlock(&m->req_lock); } p9_debug(P9_DEBUG_TRANS, "mux %p pos %d size %d\n", @@ -591,6 +593,7 @@ static void p9_conn_create(struct p9_cli INIT_LIST_HEAD(&m->mux_list); m->client = client; + spin_lock_init(&m->req_lock); INIT_LIST_HEAD(&m->req_list); INIT_LIST_HEAD(&m->unsent_req_list); INIT_WORK(&m->rq, p9_read_work); @@ -672,10 +675,10 @@ static int p9_fd_request(struct p9_clien if (m->err < 0) return m->err; - spin_lock(&client->lock); + spin_lock(&m->req_lock); req->status = REQ_STATUS_UNSENT; list_add_tail(&req->req_list, &m->unsent_req_list); - spin_unlock(&client->lock); + spin_unlock(&m->req_lock); if (test_and_clear_bit(Wpending, &m->wsched)) n = EPOLLOUT; @@ -690,11 +693,13 @@ static int p9_fd_request(struct p9_clien static int p9_fd_cancel(struct p9_client *client, struct p9_req_t *req) { + struct p9_trans_fd *ts = client->trans; + struct p9_conn *m = &ts->conn; int ret = 1; p9_debug(P9_DEBUG_TRANS, "client %p req %p\n", client, req); - spin_lock(&client->lock); + spin_lock(&m->req_lock); if (req->status == REQ_STATUS_UNSENT) { list_del(&req->req_list); @@ -702,21 +707,24 @@ static int p9_fd_cancel(struct p9_client p9_req_put(client, req); ret = 0; } - spin_unlock(&client->lock); + spin_unlock(&m->req_lock); return ret; } static int p9_fd_cancelled(struct p9_client *client, struct p9_req_t *req) { + struct p9_trans_fd *ts = client->trans; + struct p9_conn *m = &ts->conn; + p9_debug(P9_DEBUG_TRANS, "client %p req %p\n", client, req); - spin_lock(&client->lock); + spin_lock(&m->req_lock); /* Ignore cancelled request if message has been received * before lock. */ if (req->status == REQ_STATUS_RCVD) { - spin_unlock(&client->lock); + spin_unlock(&m->req_lock); return 0; } @@ -725,7 +733,8 @@ static int p9_fd_cancelled(struct p9_cli */ list_del(&req->req_list); req->status = REQ_STATUS_FLSHD; - spin_unlock(&client->lock); + spin_unlock(&m->req_lock); + p9_req_put(client, req); return 0;
