Re: [PATCH v3,2/2] media: mediatek: vcodec: adding lock to protect encoder context list

[Nicolas Dufresne <nicolas.dufresne@collabora.com>]

Le jeudi 22 février 2024 à 17:26 +0800, Yunfei Dong a écrit :
> The ctx_list will be deleted when scp getting unexpected behavior, then the
> ctx_list->next will be NULL, the kernel driver maybe access NULL pointer in
> function vpu_enc_ipi_handler when going through each context, then reboot.
> 
> Need to add lock to protect the ctx_list to make sure the ctx_list->next isn't
> NULL pointer.
> 
> Fixes: 1972e32431ed ("media: mediatek: vcodec: Fix possible invalid memory access for encoder")
> Signed-off-by: Yunfei Dong <yunfei.dong@mediatek.com>

Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>

> ---
>  .../platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c      | 4 ++--
>  .../platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.c    | 5 +++++
>  .../platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.h    | 2 ++
>  drivers/media/platform/mediatek/vcodec/encoder/venc_vpu_if.c | 2 ++
>  4 files changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c b/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c
> index 9a11a2c248045..8d578b6902148 100644
> --- a/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c
> +++ b/drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c
> @@ -73,12 +73,12 @@ static void mtk_vcodec_vpu_reset_enc_handler(void *priv)
>  
>  	dev_err(&dev->plat_dev->dev, "Watchdog timeout!!");
>  
> -	mutex_lock(&dev->dev_mutex);
> +	mutex_lock(&dev->dev_ctx_lock);
>  	list_for_each_entry(ctx, &dev->ctx_list, list) {
>  		ctx->state = MTK_STATE_ABORT;
>  		mtk_v4l2_vdec_dbg(0, ctx, "[%d] Change to state MTK_STATE_ABORT", ctx->id);
>  	}
> -	mutex_unlock(&dev->dev_mutex);
> +	mutex_unlock(&dev->dev_ctx_lock);
>  }
>  
>  static const struct mtk_vcodec_fw_ops mtk_vcodec_vpu_msg = {
> diff --git a/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.c b/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.c
> index 5db2bf3db4c54..29524cd59ce8b 100644
> --- a/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.c
> +++ b/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.c
> @@ -177,7 +177,9 @@ static int fops_vcodec_open(struct file *file)
>  	mtk_v4l2_venc_dbg(2, ctx, "Create instance [%d]@%p m2m_ctx=%p ",
>  			  ctx->id, ctx, ctx->m2m_ctx);
>  
> +	mutex_lock(&dev->dev_ctx_lock);
>  	list_add(&ctx->list, &dev->ctx_list);
> +	mutex_unlock(&dev->dev_ctx_lock);
>  
>  	mutex_unlock(&dev->dev_mutex);
>  	mtk_v4l2_venc_dbg(0, ctx, "%s encoder [%d]", dev_name(&dev->plat_dev->dev),
> @@ -212,7 +214,9 @@ static int fops_vcodec_release(struct file *file)
>  	v4l2_fh_exit(&ctx->fh);
>  	v4l2_ctrl_handler_free(&ctx->ctrl_hdl);
>  
> +	mutex_lock(&dev->dev_ctx_lock);
>  	list_del_init(&ctx->list);
> +	mutex_unlock(&dev->dev_ctx_lock);
>  	kfree(ctx);
>  	mutex_unlock(&dev->dev_mutex);
>  	return 0;
> @@ -294,6 +298,7 @@ static int mtk_vcodec_probe(struct platform_device *pdev)
>  
>  	mutex_init(&dev->enc_mutex);
>  	mutex_init(&dev->dev_mutex);
> +	mutex_init(&dev->dev_ctx_lock);
>  	spin_lock_init(&dev->irqlock);
>  
>  	snprintf(dev->v4l2_dev.name, sizeof(dev->v4l2_dev.name), "%s",
> diff --git a/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.h b/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.h
> index a042f607ed8d1..0bd85d0fb379a 100644
> --- a/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.h
> +++ b/drivers/media/platform/mediatek/vcodec/encoder/mtk_vcodec_enc_drv.h
> @@ -178,6 +178,7 @@ struct mtk_vcodec_enc_ctx {
>   *
>   * @enc_mutex: encoder hardware lock.
>   * @dev_mutex: video_device lock
> + * @dev_ctx_lock: the lock of context list
>   * @encode_workqueue: encode work queue
>   *
>   * @enc_irq: h264 encoder irq resource
> @@ -205,6 +206,7 @@ struct mtk_vcodec_enc_dev {
>  	/* encoder hardware mutex lock */
>  	struct mutex enc_mutex;
>  	struct mutex dev_mutex;
> +	struct mutex dev_ctx_lock;
>  	struct workqueue_struct *encode_workqueue;
>  
>  	int enc_irq;
> diff --git a/drivers/media/platform/mediatek/vcodec/encoder/venc_vpu_if.c b/drivers/media/platform/mediatek/vcodec/encoder/venc_vpu_if.c
> index 84ad1cc6ad171..51bb7ee141b9e 100644
> --- a/drivers/media/platform/mediatek/vcodec/encoder/venc_vpu_if.c
> +++ b/drivers/media/platform/mediatek/vcodec/encoder/venc_vpu_if.c
> @@ -47,12 +47,14 @@ static bool vpu_enc_check_ap_inst(struct mtk_vcodec_enc_dev *enc_dev, struct ven
>  	struct mtk_vcodec_enc_ctx *ctx;
>  	int ret = false;
>  
> +	mutex_lock(&enc_dev->dev_ctx_lock);
>  	list_for_each_entry(ctx, &enc_dev->ctx_list, list) {
>  		if (!IS_ERR_OR_NULL(ctx) && ctx->vpu_inst == vpu) {
>  			ret = true;
>  			break;
>  		}
>  	}
> +	mutex_unlock(&enc_dev->dev_ctx_lock);
>  
>  	return ret;
>  }