[PATCH] media: mtk-vcodec: media: mtk-vcodec: Fix a NULL pointer dereference in mtk_vcodec_fw_vpu_init()

[Greg KH]

On Tue, Jan 25, 2022 at 01:15:03AM +0800, Zhou Qingyang wrote:
> In mtk_vcodec_fw_vpu_init(), devm_kzalloc() is assigned to fw and there is
> a dereference of it right after that, which could lead to NULL pointer
> dereference on failure of devm_kzalloc().
> 
> Fix this bug by adding a NULL check of fw.
> 
> This bug was found by a static analyzer.
> 
> Builds with 'make allyesconfig' show no new warnings,
> and our static analyzer no longer warns about this code.
> 
> Fixes: 46233e91fa24 ("media: mtk-vcodec: move firmware implementations into their own files")
> Signed-off-by: Zhou Qingyang <zhou1615 at umn.edu>
> ---
> The analysis employs differential checking to identify inconsistent 
> security operations (e.g., checks or kfrees) between two code paths 
> and confirms that the inconsistent operations are not recovered in the
> current function or the callers, so they constitute bugs. 
> 
> Note that, as a bug found by static analysis, it can be a false
> positive or hard to trigger. Multiple researchers have cross-reviewed
> the bug.
> 
>  drivers/media/platform/mtk-vcodec/mtk_vcodec_fw_vpu.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/media/platform/mtk-vcodec/mtk_vcodec_fw_vpu.c b/drivers/media/platform/mtk-vcodec/mtk_vcodec_fw_vpu.c
> index cd27f637dbe7..33ae88a9f9da 100644
> --- a/drivers/media/platform/mtk-vcodec/mtk_vcodec_fw_vpu.c
> +++ b/drivers/media/platform/mtk-vcodec/mtk_vcodec_fw_vpu.c
> @@ -102,6 +102,9 @@ struct mtk_vcodec_fw *mtk_vcodec_fw_vpu_init(struct mtk_vcodec_dev *dev,
>  	vpu_wdt_reg_handler(fw_pdev, mtk_vcodec_vpu_reset_handler, dev, rst_id);
>  
>  	fw = devm_kzalloc(&dev->plat_dev->dev, sizeof(*fw), GFP_KERNEL);
> +	if (!fw)
> +		return ERR_PTR(-ENOMEM);
> +
>  	fw->type = VPU;
>  	fw->ops = &mtk_vcodec_vpu_msg;
>  	fw->pdev = fw_pdev;
> -- 
> 2.25.1
> 

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