Hi Douglas,
On Fri, Jun 30, 2023 at 2:40 PM Douglas Anderson <dianders@xxxxxxxxxxxx> wrote:
>
> KASAN reports that there's a use-after-free in
> hci_remove_adv_monitor(). Trawling through the disassembly, you can
> see that the complaint is from the access in bt_dev_dbg() under the
> HCI_ADV_MONITOR_EXT_MSFT case. The problem case happens because
> msft_remove_monitor() can end up freeing the monitor
> structure. Specifically:
> hci_remove_adv_monitor() ->
> msft_remove_monitor() ->
> msft_remove_monitor_sync() ->
> msft_le_cancel_monitor_advertisement_cb() ->
> hci_free_adv_monitor()
>
> Let's fix the problem by just stashing the relevant data when it's
> still valid.
>
> Fixes: 7cf5c2978f23 ("Bluetooth: hci_sync: Refactor remove Adv Monitor")
> Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
> ---
>
> net/bluetooth/hci_core.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index 48917c68358d..dbb2043a9112 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -1972,6 +1972,7 @@ static int hci_remove_adv_monitor(struct hci_dev *hdev,
> struct adv_monitor *monitor)
> {
> int status = 0;
> + int handle;
>
> switch (hci_get_adv_monitor_offload_ext(hdev)) {
> case HCI_ADV_MONITOR_EXT_NONE: /* also goes here when powered off */
> @@ -1980,9 +1981,10 @@ static int hci_remove_adv_monitor(struct hci_dev *hdev,
> goto free_monitor;
>
> case HCI_ADV_MONITOR_EXT_MSFT:
> + handle = monitor->handle;
> status = msft_remove_monitor(hdev, monitor);
> bt_dev_dbg(hdev, "%s remove monitor %d msft status %d",
> - hdev->name, monitor->handle, status);
> + hdev->name, handle, status);
Just move the call to bt_dev_dbg under msft_remove_monitor, also there
is no reason to print hdev->name since bt_dev_dbg already does that so
while at it we can probably fix this as well.
> break;
> }
>
> --
> 2.41.0.255.g8b1d071c50-goog
>
--
Luiz Augusto von Dentz
