| From: Bryan O'Donoghue <bryan.odonoghue@linaro.org> |
| Date: Thu, 9 Jan 2020 13:17:21 +0000 |
| Subject: usb: gadget: f_ncm: Use atomic_t to track in-flight request |
| |
| commit 5b24c28cfe136597dc3913e1c00b119307a20c7e upstream. |
| |
| Currently ncm->notify_req is used to flag when a request is in-flight. |
| ncm->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 NCM driver will |
| unconditionally free ncm->notify_req leading to a NULL pointer dereference. |
| |
| Fixes: 40d133d7f542 ("usb: gadget: f_ncm: convert to new function interface with backward compatibility") |
| 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_ncm.c | 17 +++++++++++++---- |
| 1 file changed, 13 insertions(+), 4 deletions(-) |
| |
| --- a/drivers/usb/gadget/f_ncm.c |
| +++ b/drivers/usb/gadget/f_ncm.c |
| @@ -57,6 +57,7 @@ struct f_ncm { |
| struct usb_ep *notify; |
| struct usb_request *notify_req; |
| u8 notify_state; |
| + atomic_t notify_count; |
| bool is_open; |
| |
| const struct ndp_parser_opts *parser_opts; |
| @@ -460,7 +461,7 @@ static void ncm_do_notify(struct f_ncm * |
| int status; |
| |
| /* notification already in flight? */ |
| - if (!req) |
| + if (atomic_read(&ncm->notify_count)) |
| return; |
| |
| event = req->buf; |
| @@ -500,7 +501,8 @@ static void ncm_do_notify(struct f_ncm * |
| event->bmRequestType = 0xA1; |
| event->wIndex = cpu_to_le16(ncm->ctrl_id); |
| |
| - ncm->notify_req = NULL; |
| + atomic_inc(&ncm->notify_count); |
| + |
| /* |
| * In double buffering if there is a space in FIFO, |
| * completion callback can be called right after the call, |
| @@ -510,7 +512,7 @@ static void ncm_do_notify(struct f_ncm * |
| status = usb_ep_queue(ncm->notify, req, GFP_ATOMIC); |
| spin_lock(&ncm->lock); |
| if (status < 0) { |
| - ncm->notify_req = req; |
| + atomic_dec(&ncm->notify_count); |
| DBG(cdev, "notify --> %d\n", status); |
| } |
| } |
| @@ -545,17 +547,19 @@ static void ncm_notify_complete(struct u |
| case 0: |
| VDBG(cdev, "Notification %02x sent\n", |
| event->bNotificationType); |
| + atomic_dec(&ncm->notify_count); |
| break; |
| case -ECONNRESET: |
| case -ESHUTDOWN: |
| + atomic_set(&ncm->notify_count, 0); |
| ncm->notify_state = NCM_NOTIFY_NONE; |
| break; |
| default: |
| DBG(cdev, "event %02x --> %d\n", |
| event->bNotificationType, req->status); |
| + atomic_dec(&ncm->notify_count); |
| break; |
| } |
| - ncm->notify_req = req; |
| ncm_do_notify(ncm); |
| spin_unlock(&ncm->lock); |
| } |
| @@ -1382,6 +1386,11 @@ static void ncm_unbind(struct usb_config |
| |
| usb_free_all_descriptors(f); |
| |
| + if (atomic_read(&ncm->notify_count)) { |
| + usb_ep_dequeue(ncm->notify, ncm->notify_req); |
| + atomic_set(&ncm->notify_count, 0); |
| + } |
| + |
| kfree(ncm->notify_req->buf); |
| usb_ep_free_request(ncm->notify, ncm->notify_req); |
| } |