From f95e57b66195c2de254fd16fed46a3be50ccbd62 Mon Sep 17 00:00:00 2001 From: Aleksandr Nogikh Date: Thu, 6 Aug 2026 15:26:51 +0000 Subject: [PATCH] usb: usbtest: disable dynamic ID support commit 00e2071f6d5621a5ddea311a5e6b143ae6e474af upstream. The usbtest driver relies on the driver_info field of struct usb_device_id to point to a valid struct usbtest_info descriptor. This structure contains essential test configurations, such as endpoint addresses and test modes, which are required during probe. When a user dynamically adds a new device ID via the sysfs new_id interface without specifying a reference device, the USB core initializes driver_info to 0 (NULL). When a matching device is subsequently probed, usbtest_probe() unconditionally casts driver_info to a struct usbtest_info pointer and dereferences it, leading to a NULL pointer dereference crash: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] RIP: 0010:usbtest_probe+0x3b9/0x1280 drivers/usb/misc/usbtest.c:2822 Because usbtest strictly requires pre-defined usbtest_info descriptors to function, dynamic ID binding via sysfs is fundamentally unsupported for this driver. Fix this by setting .no_dynamic_id = 1 on usbtest_driver. This instructs the USB core to skip creating the new_id and remove_id sysfs interfaces for usbtest, preventing invalid dynamic ID entries from being created. Cc: stable@vger.kernel.org Reported-by: syzbot+7e1e5911f9eac50bedc7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=7e1e5911f9eac50bedc7 Signed-off-by: Aleksandr Nogikh Tested-by: syzbot@syzkaller.appspotmail.com Link: https://patch.msgid.link/20260806152651.2370795-1-nogikh@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/misc/usbtest.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/usb/misc/usbtest.c b/drivers/usb/misc/usbtest.c index ac0d75ac2d2f..dbe87a6793ab 100644 --- a/drivers/usb/misc/usbtest.c +++ b/drivers/usb/misc/usbtest.c @@ -3053,6 +3053,7 @@ static struct usb_driver usbtest_driver = { .disconnect = usbtest_disconnect, .suspend = usbtest_suspend, .resume = usbtest_resume, + .no_dynamic_id = 1, }; /*-------------------------------------------------------------------------*/