avcodec/vp3: Fix undefined pointer arithmetic

When decoding a keyframe, last_frame and golden_frame are
not used at all and (at least when starting decoding)
are not set at all. But due to code sharing pointer arithmetic
on the NULL data-pointers of these frames has nevertheless
been performed. This is undefined behaviour and causes e.g.
"runtime error: applying non-zero offset 173440 to null pointer"
from UBSan in the vp31, vp4, theora-coeff-level64 and theora-offset
FATE-tests.

Fix this by reusing the current frame for unavailable frames.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

0 files changed, 0 insertions, 0 deletions