Sentinel segmentation fault after running voxl-uvc-server -v [camera id] -d

Alex Kushleyev

@AndriiHlyvko , we have gotten another report about this recently. It seem there is a bug in libuvc which has been fixed, but we are using older version of the library.

Inserting the following check at the line below has been reported to fix the issue:

if (strmh->got_bytes + data_len > strmh->cur_ctrl.dwMaxVideoFrameSize) {
    UVC_DEBUG("Transfer too large and will overflow the buffer. Dropping data!");
    _uvc_swap_buffers(strmh);
    return;
  }

here: https://github.com/modalai/libuvc/blob/3fb2d2fd31f215f76bd5d6782785385fd0927ce5/src/stream.c#L757

It seems the fix in the official libuvc release is here:
https://github.com/libuvc/libuvc/blob/master/src/stream.c#L779
https://github.com/libuvc/libuvc/blob/master/src/stream.c#L787

We have not fixed this officially, please look at the code snippet i provided official fix and implement something similar until we fix it.

Alex

AndriiHlyvko

Thanks @Alex-Kushleyev . Do you know if there are any differences between using the voxl fork of libuvc vs compiling the master libuvc? I was thinking of just building the master libuvc but I am not sure if modalai did any changes to it.

Alex Kushleyev

@AndriiHlyvko , you can see the changes that we made to the original fork : https://github.com/modalai/libuvc/commits/modalai-master (just the three top commits).

You may definitely try to use the latest master from the official repo, but we have not tested it. I believe there was some discussion recently about moving our code to latest, but we have not done it yet.

Alex

AndriiHlyvko

@Alex-Kushleyev just tested with latest master. The seg fault is gone and it seems to be working fine. One new problem that I have after moving to libuvc master is that the video stream from the boson+ looks wrong (the video is green ). Its only wrong for boson+ and not the boson. I'll keep debugging the issue. I was thinking maybe the boson+ sends incomplete frames in the uvc callback but I'm not sure.

AndriiHlyvko

@Alex-Kushleyev figured it out. I had a bug that I introduced. I broke the mapping between UVC_FRAME_FORMAT enum and the voxl IMAGE_FORMAT enum in my fork of the uvc-server. Right now uvc streaming is working well with the boson+

Alex Kushleyev

@AndriiHlyvko , that's great!

If you are willing to help out and share your changes on top of libuvc master, it should help us get this updated more quickly

Thank you

Alex

AndriiHlyvko

@Alex-Kushleyev sure. Should I make a merge request for it and tag you in it?

Alex Kushleyev

@AndriiHlyvko , yes and please tag @Eric-Katzfey who will probably review and merge.

Thank you!

Alex

AndriiHlyvko

Hey @Alex-Kushleyev and @Eric-Katzfey here is the MR https://gitlab.com/voxl-public/voxl-sdk/third-party/voxl-libuvc/-/merge_requests/3#59f81c123b3abbcb97274545796dd18706c3e106

Alex Kushleyev

@AndriiHlyvko , Thank you! I will ask @Eric-Katzfey to review at his convenience.