On Mon, Oct 09, 2023 at 10:08:01PM +0200, Arnd Bergmann wrote: > On Mon, Oct 9, 2023, at 21:48, Kees Cook wrote: > > On Mon, Oct 09, 2023 at 08:23:08PM +0200, Arnd Bergmann wrote: > >> On Mon, Oct 9, 2023, at 18:02, Kees Cook wrote: > >> > On Mon, Oct 09, 2023 at 05:36:55PM +0200, Arnd Bergmann wrote: > >> >> On Mon, Oct 9, 2023, at 15:48, Arnd Bergmann wrote: > >> >> > >> >> Sorry, I have to retract this, something went wrong on my > >> >> testing and I now see the same problem in some configs regardless > >> >> of whether the patch is applied or not. > >> > > >> > Perhaps turn them into macros instead? > >> > >> I just tried that and still see the problem even with the macro, > >> so whatever gcc is doing must be a different issue. Maybe it > >> has correctly found a codepath that triggers this? > >> > >> If you are able to help debug the issue better, > >> see these defconfigs for examples: > >> > >> https://pastebin.com/raw/pC8Lnrn2 > >> https://pastebin.com/raw/yb965unC > > > > This seems like a GCC bug. It is complaining about &hdev->bdaddr for > > some reason. This silences it: > > > > - if (!bacmp(&hdev->bdaddr, &ev->bdaddr)) { > > + a = hdev->bdaddr; > > + if (!bacmp(&a, &ev->bdaddr)) { > > Right, I see this addresses all instances. I tried another thing > and this also seems to address them for me: > > --- a/net/bluetooth/hci_event.c > +++ b/net/bluetooth/hci_event.c > @@ -3273,7 +3273,7 @@ static void hci_conn_request_evt(struct hci_dev *hdev, void *data, > /* Reject incoming connection from device with same BD ADDR against > * CVE-2020-26555 > */ > - if (!bacmp(&hdev->bdaddr, &ev->bdaddr)) { > + if (hdev && !bacmp(&hdev->bdaddr, &ev->bdaddr)) { > bt_dev_dbg(hdev, "Reject connection with same BD_ADDR %pMR\n", > &ev->bdaddr); > hci_reject_conn(hdev, &ev->bdaddr); > > and also this one does the trick: > > --- a/include/net/bluetooth/bluetooth.h > +++ b/include/net/bluetooth/bluetooth.h > @@ -266,7 +266,7 @@ void bt_err_ratelimited(const char *fmt, ...); > #define BT_DBG(fmt, ...) pr_debug(fmt "\n", ##__VA_ARGS__) > #endif > > -#define bt_dev_name(hdev) ((hdev) ? (hdev)->name : "null") > +#define bt_dev_name(hdev) ((hdev)->name) > > #define bt_dev_info(hdev, fmt, ...) \ > BT_INFO("%s: " fmt, bt_dev_name(hdev), ##__VA_ARGS__) > > So what is actually going on is that the bt_dev_dbg() introduces > the idea that hdev might be NULL because of the check. Oh thank you for finding that. Yeah, it looked to me like it thought hdev was NULL, but I couldn't find where. :) I think the best work-around here is your "hdev && " addition. -- Kees Cook
