In btusb_mtk_setup(), we set `btmtk_data->isopkt_intf` to: usb_ifnum_to_if(data->udev, MTK_ISO_IFNUM)
That function can return NULL in some cases. Even when it returns NULL, though, we still go on to call btusb_mtk_claim_iso_intf().
As of commit e9087e828827 ("Bluetooth: btusb: mediatek: Add locks for usb_driver_claim_interface()"), calling btusb_mtk_claim_iso_intf() when `btmtk_data->isopkt_intf` is NULL will cause a crash because we'll end up passing a bad pointer to device_lock(). Prior to that commit we'd pass the NULL pointer directly to usb_driver_claim_interface() which would detect it and return an error, which was handled.
Resolve the crash in btusb_mtk_claim_iso_intf() by adding a NULL check at the start of the function. This makes the code handle a NULL `btmtk_data->isopkt_intf` the same way it did before the problematic commit (just with a slight change to the error message printed).
Reported-by: IncogCyberpunk incogcyberpunk@proton.me Closes: http://lore.kernel.org/r/a380d061-479e-4713-bddd-1d6571ca7e86@leemhuis.info Fixes: e9087e828827 ("Bluetooth: btusb: mediatek: Add locks for usb_driver_claim_interface()") Cc: stable@vger.kernel.org Tested-by: IncogCyberpunk incogcyberpunk@proton.me Signed-off-by: Douglas Anderson dianders@chromium.org ---
Changes in v3: - Added Cc to stable. - Added IncogCyberpunk Tested-by tag. - v2: https://patch.msgid.link/20251119092641.v2.1.I1ae7aebc967e52c7c4be7aa65fbd81...
Changes in v2: - Rebase atop commit 529ac8e706c3 ("Bluetooth: ... mtk iso interface") - v1: https://patch.msgid.link/20251119085354.1.I1ae7aebc967e52c7c4be7aa65fbd81736...
drivers/bluetooth/btusb.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c index fcc62e2fb641..683ac02e964b 100644 --- a/drivers/bluetooth/btusb.c +++ b/drivers/bluetooth/btusb.c @@ -2751,6 +2751,11 @@ static void btusb_mtk_claim_iso_intf(struct btusb_data *data) if (!btmtk_data) return;
+ if (!btmtk_data->isopkt_intf) { + bt_dev_err(data->hdev, "Can't claim NULL iso interface"); + return; + } + /* * The function usb_driver_claim_interface() is documented to need * locks held if it's not called from a probe routine. The code here