Re: [PATCH 1/3] media: mediatek: vcodec: fix h264 multi statless decoder smatch warning

[AngeloGioacchino Del Regno]

Il 29/02/24 10:56, Yunfei Dong ha scritto:
> Fix smatch static checker warning for vdec_h264_req_multi_if.c.
> Leading to kernel crash when fb is NULL.
>
> Fixes: 397edc703a10 ("media: mediatek: vcodec: add h264 decoder")
> Signed-off-by: Yunfei Dong <yunfei.dong@xxxxxxxxxxxx>
> ---
>   .../vcodec/decoder/vdec/vdec_h264_req_multi_if.c         | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_h264_req_multi_if.c b/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_h264_req_multi_if.c
> index 0e741e0dc8ba..ab8e708e0df1 100644
> --- a/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_h264_req_multi_if.c
> +++ b/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_h264_req_multi_if.c
> @@ -724,11 +724,16 @@ static int vdec_h264_slice_single_decode(void *h_vdec, struct mtk_vcodec_mem *bs
>   		return vpu_dec_reset(vpu);
>   
>   	fb = inst->ctx->dev->vdec_pdata->get_cap_buffer(inst->ctx);
> +	if (!fb) {
> +		mtk_vdec_err(inst->ctx, "fb buffer is NULL");
> +		return -EBUSY;
> +	}
> +
>   	src_buf_info = container_of(bs, struct mtk_video_dec_buf, bs_buffer);
>   	dst_buf_info = container_of(fb, struct mtk_video_dec_buf, frame_buffer);
>   
> -	y_fb_dma = fb ? (u64)fb->base_y.dma_addr : 0;
> -	c_fb_dma = fb ? (u64)fb->base_c.dma_addr : 0;

You're changing the behavior here, can you please explain why this change is valid
into the commit description?

Thanks,
Angelo

> +	y_fb_dma = (u64)fb->base_y.dma_addr;
> +	c_fb_dma = (u64)fb->base_c.dma_addr;
>   	mtk_vdec_debug(inst->ctx, "[h264-dec] [%d] y_dma=%llx c_dma=%llx",
>   		       inst->ctx->decoded_frame_cnt, y_fb_dma, c_fb_dma);
>