[FFmpeg-devel] [PATCH] Fix segv when decoding gray8

Baptiste Coudurier baptiste.coudurier
Thu Jun 3 21:11:41 CEST 2010

On 06/03/2010 03:36 AM, Michael Niedermayer wrote:
> On Wed, Jun 02, 2010 at 06:39:26PM -0700, Baptiste Coudurier wrote:
>> Hi guys,
>> $subject.
>> frame->data[1] is set by avpicture_fill which is called with buf passed
>> from the demuxer.
>> However, for gray8 the data stored is only width*height, so is too small
>> for the palette, and will segv, memcpying.
>> I'm not sure what is the right fix here, buf is supposed to be const.
> as this case can only arrise from use of deprecated (and buggy) palette
> passing API, the correct (long term goal) is to change all codecs so they
> finally stop using this highly unpredictable race condition ridden api.
> until then, your patch may be ok

I don't think this is related to the API.

You cannot generate the palette for gray8 (according to pixfmt.h) 
_anyway_ since the data buffer is not big enough, since it comes from 
the demuxer itself.
So either, the picture needs to be copied and the palette generated, or 
we skip the palette generation.

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