Re: [FFmpeg-devel] [PATCH v1] avcodec/vp9_superframe_split_bsf: Fix for possible null pointer dereference

[Andreas Rheinhardt <andreas.rheinhardt@outlook.com>]

Dawid Kozinski/Multimedia (PLT) /SRPOL/Staff Engineer/Samsung Electronics:
> 
> Pointer  ctx->priv_data->buffer_pkt->data, that can have only NULL value (checked at vp9_superframe_split_bsf.c:48), is dereferenced at vp9_superframe_split_bsf.c:57.
> 

The rationale for a patch should be included in the commit message and
not be sent as a reply to the actual patch.

The warning is nonsense and you are breaking the whole BSF with this
patch. It is perfectly normal for buffer_pkt->data to be NULL at line 48
and to be != NULL at line 57: There is a ff_bsf_get_packet_ref() in
between which fills the packet.

- Andreas

> 
>> -----Original Message-----
>> From: Dawid Kozinski <d.kozinski@samsung.com>
>> Sent: piątek, 6 października 2023 13:02
>> To: d.frankiewic@samsung.com; ffmpeg-devel@ffmpeg.org
>> Cc: Dawid Kozinski <d.kozinski@samsung.com>
>> Subject: [PATCH v1] avcodec/vp9_superframe_split_bsf: Fix for possible null
>> pointer dereference
>>
>> Signed-off-by: Dawid Kozinski <d.kozinski@samsung.com>
>> ---
>>  libavcodec/vp9_superframe_split_bsf.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/libavcodec/vp9_superframe_split_bsf.c
>> b/libavcodec/vp9_superframe_split_bsf.c
>> index cddd48119c..4f94afc6d9 100644
>> --- a/libavcodec/vp9_superframe_split_bsf.c
>> +++ b/libavcodec/vp9_superframe_split_bsf.c
>> @@ -45,7 +45,7 @@ static int vp9_superframe_split_filter(AVBSFContext *ctx,
>> AVPacket *out)
>>      int i, j, ret, marker;
>>      int is_superframe = !!s->buffer_pkt->data;
>>
>> -    if (!s->buffer_pkt->data) {
>> +    if (s->buffer_pkt->data) {
>>          ret = ff_bsf_get_packet_ref(ctx, s->buffer_pkt);
>>          if (ret < 0)
>>              return ret;
>> --
>> 2.25.1
> 
> 

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