From e3ed79d11b2716aaca68ae9afdc79dddae53bdc9 Mon Sep 17 00:00:00 2001 From: Bryan O'Donoghue Date: Thu, 9 Jan 2020 13:17:22 +0000 Subject: [PATCH] usb: gadget: f_ecm: Use atomic_t to track in-flight request commit d710562e01c48d59be3f60d58b7a85958b39aeda upstream. Currently ecm->notify_req is used to flag when a request is in-flight. ecm->notify_req is set to NULL and when a request completes it is subsequently reset. This is fundamentally buggy in that the unbind logic of the ECM driver will unconditionally free ecm->notify_req leading to a NULL pointer dereference. Fixes: da741b8c56d6 ("usb ethernet gadget: split CDC Ethernet function") Cc: stable Signed-off-by: Bryan O'Donoghue Signed-off-by: Felipe Balbi Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_ecm.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/usb/gadget/function/f_ecm.c b/drivers/usb/gadget/function/f_ecm.c index 460d5d7..7f5cf48 100644 --- a/drivers/usb/gadget/function/f_ecm.c +++ b/drivers/usb/gadget/function/f_ecm.c @@ -52,6 +52,7 @@ struct f_ecm { struct usb_ep *notify; struct usb_request *notify_req; u8 notify_state; + atomic_t notify_count; bool is_open; /* FIXME is_open needs some irq-ish locking @@ -380,7 +381,7 @@ static void ecm_do_notify(struct f_ecm *ecm) int status; /* notification already in flight? */ - if (!req) + if (atomic_read(&ecm->notify_count)) return; event = req->buf; @@ -420,10 +421,10 @@ static void ecm_do_notify(struct f_ecm *ecm) event->bmRequestType = 0xA1; event->wIndex = cpu_to_le16(ecm->ctrl_id); - ecm->notify_req = NULL; + atomic_inc(&ecm->notify_count); status = usb_ep_queue(ecm->notify, req, GFP_ATOMIC); if (status < 0) { - ecm->notify_req = req; + atomic_dec(&ecm->notify_count); DBG(cdev, "notify --> %d\n", status); } } @@ -448,17 +449,19 @@ static void ecm_notify_complete(struct usb_ep *ep, struct usb_request *req) switch (req->status) { case 0: /* no fault */ + atomic_dec(&ecm->notify_count); break; case -ECONNRESET: case -ESHUTDOWN: + atomic_set(&ecm->notify_count, 0); ecm->notify_state = ECM_NOTIFY_NONE; break; default: DBG(cdev, "event %02x --> %d\n", event->bNotificationType, req->status); + atomic_dec(&ecm->notify_count); break; } - ecm->notify_req = req; ecm_do_notify(ecm); } @@ -907,6 +910,11 @@ static void ecm_unbind(struct usb_configuration *c, struct usb_function *f) usb_free_all_descriptors(f); + if (atomic_read(&ecm->notify_count)) { + usb_ep_dequeue(ecm->notify, ecm->notify_req); + atomic_set(&ecm->notify_count, 0); + } + kfree(ecm->notify_req->buf); usb_ep_free_request(ecm->notify, ecm->notify_req); } -- 2.7.4