3.16.84-rc1 review patch. If anyone has any objections, please let me know.
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From: Bryan O'Donoghue bryan.odonoghue@linaro.org
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") Signed-off-by: Bryan O'Donoghue bryan.odonoghue@linaro.org Signed-off-by: Felipe Balbi balbi@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [bwh: Backported to 3.16: adjust filename] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/usb/gadget/f_ecm.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)
--- a/drivers/usb/gadget/f_ecm.c +++ b/drivers/usb/gadget/f_ecm.c @@ -56,6 +56,7 @@ 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 @@ -384,7 +385,7 @@ static void ecm_do_notify(struct f_ecm * int status;
/* notification already in flight? */ - if (!req) + if (atomic_read(&ecm->notify_count)) return;
event = req->buf; @@ -424,10 +425,10 @@ static void ecm_do_notify(struct f_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); } } @@ -452,17 +453,19 @@ static void ecm_notify_complete(struct u 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); }
@@ -922,6 +925,11 @@ static void ecm_unbind(struct usb_config
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); }