[FFmpeg-devel] [PATCH] checkasm/blockdsp: don't randomize the buffers for fill_block_tab

[Andreas Rheinhardt]

Martin Storsjö:
> On Mon, 6 May 2024, James Almer wrote:
> 
>> It ignores and overwrites the previous values.
>> Fixes running the test under ubsan.
>>
>> Signed-off-by: James Almer <jamrial at gmail.com>
>> ---
>> tests/checkasm/blockdsp.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
> 
> The change is probably correct, but what issue is ubsan complaining
> about? If this would just be a dead store of unused random values, that
> shouldn't be an ubsan issue in general, right?
> 

UBSan complains about unaligned stores in randomize_buffers; which is
obvious given that i is incremented by 1, not by 2. I sent a patch that
fixes this without removing randomization:
https://ffmpeg.org/pipermail/ffmpeg-devel/2024-May/326945.html

(Ideally, this test should be extended to cover cases of stride != width.)

- Andreas