media: mediatek: vcodec: adding lock to protect encoder context list

Add a lock for the ctx_list, to avoid accessing a NULL pointer
within the 'vpu_enc_ipi_handler' function when the ctx_list has
been deleted due to an unexpected behavior on the SCP IP block.

Fixes: 1972e324 ("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>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

drivers/media/platform/mediatek/vcodec/common/mtk_vcodec_fw_vpu.c

@@ -65,12 +65,12 @@ 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 = {

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",

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;

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;
 }