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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 <nogikh@google.com> Tested-by: syzbot@syzkaller.appspotmail.com Link: https://patch.msgid.link/20260806152651.2370795-1-nogikh@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>