* [PATCH] Bluetooth: hci_ldisc: Postpone HCI_UART_PROTO_READY bit set in hci_uart_set_proto()
@ 2019-02-23 4:33 Kefeng Wang
2019-02-24 1:12 ` Jeremy Cline
2019-02-26 8:56 ` Marcel Holtmann
0 siblings, 2 replies; 3+ messages in thread
From: Kefeng Wang @ 2019-02-23 4:33 UTC (permalink / raw)
To: Marcel Holtmann, linux-bluetooth, linux-kernel
Cc: Jeremy Cline, Johan Hedberg, Kefeng Wang, syzbot+899a33dc0fa0dbaf06a6
task A: task B:
hci_uart_set_proto flush_to_ldisc
- p->open(hu) -> h5_open //alloc h5 - receive_buf
- set_bit HCI_UART_PROTO_READY - tty_port_default_receive_buf
- hci_uart_register_dev - tty_ldisc_receive_buf
- hci_uart_tty_receive
- test_bit HCI_UART_PROTO_READY
- h5_recv
- clear_bit HCI_UART_PROTO_READY while() {
- p->open(hu) -> h5_close //free h5
- h5_rx_3wire_hdr
- h5_reset() //use-after-free
}
It could use ioctl to set hci uart proto, but there is
a use-after-free issue when hci_uart_register_dev() fail in
hci_uart_set_proto(), see stack above, fix this by setting
HCI_UART_PROTO_READY bit only when hci_uart_register_dev()
return success.
Reported-by: syzbot+899a33dc0fa0dbaf06a6@syzkaller.appspotmail.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
drivers/bluetooth/hci_ldisc.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index 4918fefc4a6f..9562e72c1ae5 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -696,14 +696,13 @@ static int hci_uart_set_proto(struct hci_uart *hu, int id)
return -EPROTONOSUPPORT;
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);
return err;
}
+ set_bit(HCI_UART_PROTO_READY, &hu->flags);
return 0;
}
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] Bluetooth: hci_ldisc: Postpone HCI_UART_PROTO_READY bit set in hci_uart_set_proto()
2019-02-23 4:33 [PATCH] Bluetooth: hci_ldisc: Postpone HCI_UART_PROTO_READY bit set in hci_uart_set_proto() Kefeng Wang
@ 2019-02-24 1:12 ` Jeremy Cline
2019-02-26 8:56 ` Marcel Holtmann
1 sibling, 0 replies; 3+ messages in thread
From: Jeremy Cline @ 2019-02-24 1:12 UTC (permalink / raw)
To: Kefeng Wang
Cc: Marcel Holtmann, linux-bluetooth, linux-kernel, Johan Hedberg,
syzbot+899a33dc0fa0dbaf06a6
On Sat, Feb 23, 2019 at 12:33:27PM +0800, Kefeng Wang wrote:
> task A: task B:
> hci_uart_set_proto flush_to_ldisc
> - p->open(hu) -> h5_open //alloc h5 - receive_buf
> - set_bit HCI_UART_PROTO_READY - tty_port_default_receive_buf
> - hci_uart_register_dev - tty_ldisc_receive_buf
> - hci_uart_tty_receive
> - test_bit HCI_UART_PROTO_READY
> - h5_recv
> - clear_bit HCI_UART_PROTO_READY while() {
> - p->open(hu) -> h5_close //free h5
I think commit 32a7b4cbe93b ("Bluetooth: hci_ldisc: Initialize hci_dev
before open()") in made this worse by inadvertently changing this from
- clear_bit HCI_UART_PROTO_READY
- p->close(hu) -> h5_close //free h5
to
- p->close(hu) -> h5_close //free h5
- clear_bit HCI_UART_PROTO_READY
because the close call got moved into hci_uart_register_dev(). I guess
that made the race window sufficiently wide to be easily reproducible,
but it looks like it was present even before that commit.
> - h5_rx_3wire_hdr
> - h5_reset() //use-after-free
> }
>
> It could use ioctl to set hci uart proto, but there is
> a use-after-free issue when hci_uart_register_dev() fail in
> hci_uart_set_proto(), see stack above, fix this by setting
> HCI_UART_PROTO_READY bit only when hci_uart_register_dev()
> return success.
>
> Reported-by: syzbot+899a33dc0fa0dbaf06a6@syzkaller.appspotmail.com
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
> drivers/bluetooth/hci_ldisc.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
> index 4918fefc4a6f..9562e72c1ae5 100644
> --- a/drivers/bluetooth/hci_ldisc.c
> +++ b/drivers/bluetooth/hci_ldisc.c
> @@ -696,14 +696,13 @@ static int hci_uart_set_proto(struct hci_uart *hu, int id)
> return -EPROTONOSUPPORT;
>
> 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);
> return err;
> }
>
> + set_bit(HCI_UART_PROTO_READY, &hu->flags);
> return 0;
> }
>
> --
> 2.20.1
>
For what it's worth:
Reviewed-by: Jeremy Cline <jcline@redhat.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] Bluetooth: hci_ldisc: Postpone HCI_UART_PROTO_READY bit set in hci_uart_set_proto()
2019-02-23 4:33 [PATCH] Bluetooth: hci_ldisc: Postpone HCI_UART_PROTO_READY bit set in hci_uart_set_proto() Kefeng Wang
2019-02-24 1:12 ` Jeremy Cline
@ 2019-02-26 8:56 ` Marcel Holtmann
1 sibling, 0 replies; 3+ messages in thread
From: Marcel Holtmann @ 2019-02-26 8:56 UTC (permalink / raw)
To: Kefeng Wang
Cc: open list:BLUETOOTH DRIVERS, linux-kernel, Jeremy Cline,
Johan Hedberg, syzbot+899a33dc0fa0dbaf06a6
Hi Kefeng,
> task A: task B:
> hci_uart_set_proto flush_to_ldisc
> - p->open(hu) -> h5_open //alloc h5 - receive_buf
> - set_bit HCI_UART_PROTO_READY - tty_port_default_receive_buf
> - hci_uart_register_dev - tty_ldisc_receive_buf
> - hci_uart_tty_receive
> - test_bit HCI_UART_PROTO_READY
> - h5_recv
> - clear_bit HCI_UART_PROTO_READY while() {
> - p->open(hu) -> h5_close //free h5
> - h5_rx_3wire_hdr
> - h5_reset() //use-after-free
> }
>
> It could use ioctl to set hci uart proto, but there is
> a use-after-free issue when hci_uart_register_dev() fail in
> hci_uart_set_proto(), see stack above, fix this by setting
> HCI_UART_PROTO_READY bit only when hci_uart_register_dev()
> return success.
>
> Reported-by: syzbot+899a33dc0fa0dbaf06a6@syzkaller.appspotmail.com
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
> drivers/bluetooth/hci_ldisc.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
patch has been applied to bluetooth-next tree.
Regards
Marcel
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-02-23 4:33 [PATCH] Bluetooth: hci_ldisc: Postpone HCI_UART_PROTO_READY bit set in hci_uart_set_proto() Kefeng Wang
2019-02-24 1:12 ` Jeremy Cline
2019-02-26 8:56 ` Marcel Holtmann
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