On Mon, Oct 16, 2017 at 03:12:07PM -0400, Alan Stern wrote: > On Mon, 16 Oct 2017, Hans de Goede wrote: > > > Taking the uurb->buffer_length userspace passes in as a maximum for the > > actual urbs transfer_buffer_length causes 2 serious issues: > > > > 1) It breaks isochronous support for all userspace apps using libusb, > > as existing libusb versions pass in 0 for uurb->buffer_length, > > relying on the kernel using the lenghts of the usbdevfs_iso_packet_desc > > descriptors passed in added together as buffer length. > > > > This for example causes redirection of USB audio and Webcam's into > > virtual machines using qemu-kvm to no longer work. This is a userspace > > ABI break and as such must be reverted. > > > > Note that the original commit does not protect other users / the > > kernels memory, it only stops the userspace process making the call > > from shooting itself in the foot. > > Okay, breaking userspace is reason enough all by itself to revert this > change. I didn't realize that libusb sets the buffer_length to 0 for > isochronous URBs. > Yeah... I should have seen how this worked just from reading the code. :/ regards, dan carpenter -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
