linux-kernel - Re: bluetooth: use-after-free in vhci_send

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Date:	Fri, 18 Mar 2016 17:59:01 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	Marcel Holtmann <marcel@...tmann.org>,
	Dmitry Vyukov <dvyukov@...gle.com>
Cc:	"Gustavo F. Padovan" <gustavo@...ovan.org>,
	Johan Hedberg <johan.hedberg@...il.com>,
	linux-bluetooth <linux-bluetooth@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	syzkaller <syzkaller@...glegroups.com>,
	Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Sasha Levin <sasha.levin@...cle.com>
Subject: Re: bluetooth: use-after-free in vhci_send_frame

On 03/08/2016, 07:32 PM, Marcel Holtmann wrote:
> that means very little to me actually. So is the real issue caused by opening /dev/vhci or is that theoretical one via some internal kernel compile time feature.

Hi, what do you think about this one?

--- a/drivers/bluetooth/hci_vhci.c
+++ b/drivers/bluetooth/hci_vhci.c
@@ -196,6 +196,11 @@ static inline ssize_t vhci_get_user(stru

                cancel_delayed_work_sync(&data->open_timeout);

+               if (data->hdev) {
+                       kfree_skb(skb);
+                       return -EBADFD;
+               }
+
                opcode = *((__u8 *) skb->data);
                skb_pull(skb, 1);


open_timeout could be in progress (raced with us) and _sync cancel
waited for vhci_create_device to actually finish and create the device
the second time.

thanks,
-- 
js
suse labs