From: Jeremy Cline <jcline@redhat.com>
To: Marcel Holtmann <marcel@holtmann.org>,
Johan Hedberg <johan.hedberg@gmail.com>
Cc: linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org,
Jeremy Cline <jcline@redhat.com>,
syzbot+257790c15bcdef6fe00c@syzkaller.appspotmail.com
Subject: [PATCH] Bluetooth: hci_ldisc: Initialize hci_dev before open()
Date: Wed, 6 Feb 2019 12:54:16 -0500 [thread overview]
Message-ID: <20190206175416.4627-1-jcline@redhat.com> (raw)
The hci_dev struct hdev is referenced in work queues and timers started
by open() in some protocols. This creates a race between the
initialization function and the work or timer which can result hdev
being dereferenced while it is still null.
The syzbot report contains a reliable reproducer which causes a null
pointer dereference of hdev in hci_uart_write_work() by making the
memory allocation for hdev fail.
To fix this, ensure hdev is valid from before calling a protocol's
open() until after calling a protocol's close().
Reported-by: syzbot+257790c15bcdef6fe00c@syzkaller.appspotmail.com
Signed-off-by: Jeremy Cline <jcline@redhat.com>
---
drivers/bluetooth/hci_ldisc.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index fbf7b4df23ab..4918fefc4a6f 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -207,11 +207,11 @@ void hci_uart_init_work(struct work_struct *work)
err = hci_register_dev(hu->hdev);
if (err < 0) {
BT_ERR("Can't register HCI device");
+ clear_bit(HCI_UART_PROTO_READY, &hu->flags);
+ hu->proto->close(hu);
hdev = hu->hdev;
hu->hdev = NULL;
hci_free_dev(hdev);
- clear_bit(HCI_UART_PROTO_READY, &hu->flags);
- hu->proto->close(hu);
return;
}
@@ -616,6 +616,7 @@ static void hci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
static int hci_uart_register_dev(struct hci_uart *hu)
{
struct hci_dev *hdev;
+ int err;
BT_DBG("");
@@ -659,11 +660,22 @@ static int hci_uart_register_dev(struct hci_uart *hu)
else
hdev->dev_type = HCI_PRIMARY;
+ /* Only call open() for the protocol after hdev is fully initialized as
+ * open() (or a timer/workqueue it starts) may attempt to reference it.
+ */
+ err = hu->proto->open(hu);
+ if (err) {
+ hu->hdev = NULL;
+ hci_free_dev(hdev);
+ return err;
+ }
+
if (test_bit(HCI_UART_INIT_PENDING, &hu->hdev_flags))
return 0;
if (hci_register_dev(hdev) < 0) {
BT_ERR("Can't register HCI device");
+ hu->proto->close(hu);
hu->hdev = NULL;
hci_free_dev(hdev);
return -ENODEV;
@@ -683,17 +695,12 @@ static int hci_uart_set_proto(struct hci_uart *hu, int id)
if (!p)
return -EPROTONOSUPPORT;
- err = p->open(hu);
- if (err)
- return err;
-
hu->proto = p;
set_bit(HCI_UART_PROTO_READY, &hu->flags);
err = hci_uart_register_dev(hu);
if (err) {
clear_bit(HCI_UART_PROTO_READY, &hu->flags);
- p->close(hu);
return err;
}
--
2.20.1
next reply other threads:[~2019-02-06 17:54 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-06 17:54 Jeremy Cline [this message]
2019-02-18 12:55 ` [PATCH] Bluetooth: hci_ldisc: Initialize hci_dev before open() Marcel Holtmann
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