From: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
To: balbi@kernel.org, gregkh@linuxfoundation.org,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Subject: [PATCH 1/2] usb: gadget: f_ncm: Use atomic_t to track in-flight request
Date: Thu, 9 Jan 2020 13:17:21 +0000 [thread overview]
Message-ID: <20200109131722.4090238-2-bryan.odonoghue@linaro.org> (raw)
In-Reply-To: <20200109131722.4090238-1-bryan.odonoghue@linaro.org>
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: 40d133d7f5426 ("usb: gadget: f_ncm: convert to new function interface
with backward compatibility")
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
---
drivers/usb/gadget/function/f_ncm.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/gadget/function/f_ncm.c b/drivers/usb/gadget/function/f_ncm.c
index 2d6e76e4cffa..1d900081b1f0 100644
--- a/drivers/usb/gadget/function/f_ncm.c
+++ b/drivers/usb/gadget/function/f_ncm.c
@@ -53,6 +53,7 @@ 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;
@@ -547,7 +548,7 @@ static void ncm_do_notify(struct f_ncm *ncm)
int status;
/* notification already in flight? */
- if (!req)
+ if (atomic_read(&ncm->notify_count))
return;
event = req->buf;
@@ -587,7 +588,8 @@ static void ncm_do_notify(struct f_ncm *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,
@@ -597,7 +599,7 @@ static void ncm_do_notify(struct f_ncm *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);
}
}
@@ -632,17 +634,19 @@ static void ncm_notify_complete(struct usb_ep *ep, struct usb_request *req)
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);
}
@@ -1649,6 +1653,11 @@ static void ncm_unbind(struct usb_configuration *c, struct usb_function *f)
ncm_string_defs[0].id = 0;
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);
}
--
2.24.0
next prev parent reply other threads:[~2020-01-09 13:17 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-09 13:17 [PATCH 0/2] Fix two NULL pointer dereferences when role-switching Bryan O'Donoghue
2020-01-09 13:17 ` Bryan O'Donoghue [this message]
2020-01-09 13:17 ` [PATCH 2/2] usb: gadget: f_ecm: Use atomic_t to track in-flight request Bryan O'Donoghue
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