Bug#853798: mpv: Segfaults on TV input

[James Cowgill]

Hi,

On 01/02/17 00:27, Frédéric Brière wrote:
> Package: mpv
> Version: 0.23.0-1
> Severity: important
> 
> mpv quickly segfaults (before displaying any video) on TV input:
> 
>   $ mpv tv://
>   Playing: tv://
>   [tv] Selected driver: v4l2
>   [tv]  name: Video 4 Linux 2 input
>   [tv] Selected device: BT878 video (Hauppauge (bt878))
>   [tv]  Tuner cap:
>   [tv]  Tuner rxs: MONO
>   [tv]  Capabilities:  video capture  video overlay  VBI capture device  tuner  read/write  streaming
>   [tv]  supported norms: 0 = NTSC; 1 = NTSC-M; 2 = NTSC-M-JP; 3 = NTSC-M-KR; 4 = PAL; 5 = PAL-BG; 6 = PAL-H; 7 = PAL-I; 8 = PAL-DK; 9 = PAL-M; 10 = PAL-N; 11 = PAL-Nc; 12 = PAL-60; 13 = SECAM; 14 = SECAM-B; 15 = SECAM-G; 16 = SECAM-H; 17 = SECAM-DK; 18 = SECAM-L; 19 = SECAM-Lc;
>   [tv]  inputs: 0 = Television; 1 = Composite1; 2 = S-Video; 3 = Composite3;
>   [tv]  Current input: 0
>   [tv]  Current format: YVU420
>   [tv] current audio mode is : MONO
>   Segmentation fault
> 
> 
> For what it's worth, this bug does not seem to be present in MPlayer.
> 
> Backtrace follows.  Let me know if I can be of any further help.

Unfortunately I can't reproduce this issue (I don't have any TV input
devices except a webcam which works OK) so I'm not sure there's much
that I can do but there are some things you could try:

- Try building upstream git mpv. If that also fails you can report a bug
upstream and they can have a look at it.

- Does the segfault happen with older versions of mpv? You can find them
here: http://snapshot.debian.org/package/mpv/

- Running "bt all" in gdb might be useful.

- Running mpv in valgrind might also help (if the bug is memory related).

> #0  0x0000557aee3e8dc7 in set_norm_and_freq (tvh=tvh at entry=0x7f397001e700, 
>     chan=0x5a00000005) at ../stream/tv.c:430
> #1  0x0000557aee3e94d6 in open_tv (tvh=tvh at entry=0x7f397001e700)
>     at ../stream/tv.c:599

Whatever the bug is, it seems likely that the "chan" pointer
(0x5a00000005) is garbage so the bug may be in open_tv.

Thanks,
James

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