On Tue, 9 Mar 2021 at 18:24, Gerd Hoffmann <kra...@redhat.com> wrote:
> On Tue, Mar 09, 2021 at 10:54:15AM +1100, Ben Leslie wrote: > > When usb_host_get_port is called for a root-hub device what string should > > be output in the port parameter? > > Just the port number, as string. > > (and in case this isn't a root port the hub port number(s) are appended, > separated by a dot). > > > The current behaviour writes a string with whatever stack value happened > to > > be in the paths stack array. > > Huh? Isn't paths updated by the libusb_get_port_numbers() call? > libusb_get_port_numbers() can return zero (for the root hub); or at least it does on the Linux systems I tried. If that happens path[0] won't be changed by libusb_get_port_numbers. The rest of the function assumes that the path is at least 1 item long and unconditionally access path[0], which isn't true if a root-hub device is passed to the function. Of course, reading the current code more carefully, usb_host_get_port is never actually called with a hub device (let alone a root hub), so I guess it is a valid assumption that libusb_get_port_numbers will always return at least 1 in the non-error path. I hit the problem as I was trying to reuse the function with a hub device, so my bad. Thanks, Ben
