Re: [Mesa-dev] [mesa-20.3.2] NULL pointer dereference in vl_compositor_yuv_deint_full

[Thong Thai]

Hi Alexander,

Guess I should add a check to see if it can create a non-interlaced 
video buffer, and if not, return what it would have returned before, 
when trying to derive an image from an interlaced buffer:

return VA_STATUS_ERROR_OPERATION_FAILED;

Thanks,

Thong Thai

On 2021-01-03 3:38 p.m., Alexander Kapshuk wrote:
NVIDIA chip affected:
01:00.0 VGA compatible controller: NVIDIA Corporation GT216 [GeForce
210] (rev a1)

The null pointer dereference occurs here:
Thread 27 "vlc" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fff8f7c1640 (LWP 79292)]
0x00007fff8d59d1da in vl_compositor_yuv_deint_full (s=0x7fff980e8518,
c=0x7fff980e83d8, src=0x7fff98670030, dst=0x0,
src_rect=0x7fff8f7c0470, dst_rect=0x7fff8f7c0460,
deinterlace=VL_COMPOSITOR_WEAVE) at
../mesa-20.3.2/src/gallium/auxiliary/vl/vl_compositor.c:689
689     dst_surfaces = dst->get_surfaces(dst); //dst==NULL

=> 0x00007fff8d5981da <+42>:    call   *0x38(%rcx) //rcx is dst
(gdb) i r rcx
rcx            0x0                 0

(gdb) bt
#0  0x00007fff8d59d1da in vl_compositor_yuv_deint_full
(s=0x7fff980e8518, c=0x7fff980e83d8, src=0x7fff98670030, dst=0x0,
src_rect=0x7fff8f7c0470, dst_rect=0x7fff8f7c0460,
deinterlace=VL_COMPOSITOR_WEAVE) at
../mesa-20.3.2/src/gallium/auxiliary/vl/vl_compositor.c:689
#1  0x00007fff8d58a29b in vlVaDeriveImage (ctx=0x7fff980c1590,
surface=<optimized out>, image=0x7fff8f7c05e0)    at
../mesa-20.3.2/src/gallium/frontends/va/image.c:321
#2  0x00007fff91485799 in vaDeriveImage () at /usr/lib/libva.so.2
#3  0x00007fff8e2256d2 in  () at
/usr/lib/vlc/plugins/video_output/libglconv_vaapi_x11_plugin.so
#4  0x00007fff8e224189 in  () at
/usr/lib/vlc/plugins/video_output/libglconv_vaapi_x11_plugin.so
#5  0x00007fff8f6b1896 in  () at
/usr/lib/vlc/plugins/video_output/libgl_plugin.so
#6  0x00007fff8f6b86db in  () at
/usr/lib/vlc/plugins/video_output/libgl_plugin.so
#7  0x00007ffff7d07cee in  () at /usr/lib/libvlccore.so.9
#8  0x00007ffff7cfa019 in  () at /usr/lib/libvlccore.so.9
#9  0x00007ffff7cfbf9e in  () at /usr/lib/libvlccore.so.9
#10 0x00007ffff7f623e9 in start_thread () at /usr/lib/libpthread.so.0
#11 0x00007ffff7e8a293 in clone () at /usr/lib/libc.so.6

mesa-20.3.2/src/gallium/frontends/va/image.c:312,313
VAStatus
vlVaDeriveImage(VADriverContextP ctx, VASurfaceID surface, VAImage *image)
{
...
          new_template.interlaced = false; //create_video_buffer
returns NULL if new_template.interlaced is set to false See below.
          new_buffer = drv->pipe->create_video_buffer(drv->pipe, &new_template);
...
          vl_compositor_yuv_deint_full(&drv->cstate, &drv->compositor,
                            surf->buffer, new_buffer,
                            &src_rect, &dst_rect,
                            VL_COMPOSITOR_WEAVE);
...
}

mesa-20.3.2/src/gallium/drivers/nouveau/nv50/nv84_video.c:618,621
struct pipe_video_buffer *
nv84_video_buffer_create(struct pipe_context *pipe,
                          const struct pipe_video_buffer *template)
{
...
    if (!template->interlaced) { //set to false in vlVaDeriveImage. See above
       debug_printf("Require interlaced video buffers\n");
       return NULL;
    }
...
}

Here's the commit that introduced the null pointer dereference in
question, 
https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.freedesktop.org%2Fmesa%2Fmesa%2F-%2Fcommit%2Ffcb558321e65b62244a11e0066bb8713b1854721&amp;data=04%7C01%7Cthong.thai%40amd.com%7C05879305275d42ce31ff08d8b0279037%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637453031560482800%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=Cx3j7nIJU5Qoc%2BNpP5UTdRHJyS7hguLbWmoJsybTu0Q%3D&amp;reserved=0.
Please advise on the further course of action.
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