Re: [PATCH 1/3] drm/mediatek: Fix crash at using pkt->cl->chan in cmdq_pkt_finalize

From: Chun-Kuang Hu
Date: Wed Sep 29 2021 - 10:52:12 EST

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Hi, Jason:

jason-jh.lin <jason-jh.lin@xxxxxxxxxxxx> 於 2021年9月29日週三下午3:02寫道：
>
> Because mtk_drm_crtc_create_pkt didn't assign pkt->cl, it will
> crash at using pkt->cl->chan in cmdq_pkt_finalize.
>
> So add struct cmdq_client and let mtk_drm_crtc instance define
> cmdq_client as:
>
> struct mtk_drm_crtc {
> /* client instance data */
> struct cmdq_client cmdq_client;
> };
>
> and in rx_callback function can use pkt->cl to get
> struct cmdq_client.
>
> Fixes: f4be17cd5b14 ("drm/mediatek: Remove struct cmdq_client")
> Signed-off-by: jason-jh.lin <jason-jh.lin@xxxxxxxxxxxx>
> ---
> drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 73 +++++++++++++------------
> 1 file changed, 38 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> index 5f81489fc60c..e98871a8c961 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> @@ -52,8 +52,7 @@ struct mtk_drm_crtc {
> bool pending_async_planes;
>
> #if IS_REACHABLE(CONFIG_MTK_CMDQ)
> - struct mbox_client cmdq_cl;
> - struct mbox_chan *cmdq_chan;
> + struct cmdq_client cmdq_client;
> struct cmdq_pkt cmdq_handle;
> u32 cmdq_event;
> u32 cmdq_vblank_cnt;
> @@ -227,8 +226,8 @@ struct mtk_ddp_comp *mtk_drm_ddp_comp_for_plane(struct drm_crtc *crtc,
> }
>
> #if IS_REACHABLE(CONFIG_MTK_CMDQ)
> -static int mtk_drm_cmdq_pkt_create(struct mbox_chan *chan, struct cmdq_pkt *pkt,
> - size_t size)
> +static int mtk_drm_cmdq_pkt_create(struct cmdq_client *client, struct cmdq_pkt *pkt,
> + size_t size)
> {
> struct device *dev;
> dma_addr_t dma_addr;
> @@ -239,8 +238,9 @@ static int mtk_drm_cmdq_pkt_create(struct mbox_chan *chan, struct cmdq_pkt *pkt,
> return -ENOMEM;
> }
> pkt->buf_size = size;
> + pkt->cl = (void *)client;
>
> - dev = chan->mbox->dev;
> + dev = client->chan->mbox->dev;
> dma_addr = dma_map_single(dev, pkt->va_base, pkt->buf_size,
> DMA_TO_DEVICE);
> if (dma_mapping_error(dev, dma_addr)) {
> @@ -255,9 +255,11 @@ static int mtk_drm_cmdq_pkt_create(struct mbox_chan *chan, struct cmdq_pkt *pkt,
> return 0;
> }
>
> -static void mtk_drm_cmdq_pkt_destroy(struct mbox_chan *chan, struct cmdq_pkt *pkt)
> +static void mtk_drm_cmdq_pkt_destroy(struct cmdq_pkt *pkt)
> {
> - dma_unmap_single(chan->mbox->dev, pkt->pa_base, pkt->buf_size,
> + struct cmdq_client *client = (struct cmdq_client *)pkt->cl;
> +
> + dma_unmap_single(client->chan->mbox->dev, pkt->pa_base, pkt->buf_size,
> DMA_TO_DEVICE);
> kfree(pkt->va_base);
> kfree(pkt);
> @@ -265,8 +267,9 @@ static void mtk_drm_cmdq_pkt_destroy(struct mbox_chan *chan, struct cmdq_pkt *pk
>
> static void ddp_cmdq_cb(struct mbox_client *cl, void *mssg)
> {
> - struct mtk_drm_crtc *mtk_crtc = container_of(cl, struct mtk_drm_crtc, cmdq_cl);
> struct cmdq_cb_data *data = mssg;
> + struct cmdq_pkt *pkt = data->pkt;
> + struct mtk_drm_crtc *mtk_crtc = container_of(pkt->cl, struct mtk_drm_crtc, cmdq_client);

I think you should use cl to find struct cmdq_client, and then use
struct cmdq_clint to find struct mtk_drm_crtc.
In the next patch, you could remove the local variable pkt.

> struct mtk_crtc_state *state;
> unsigned int i;
>
> @@ -299,7 +302,7 @@ static void ddp_cmdq_cb(struct mbox_client *cl, void *mssg)
> }
>
> mtk_crtc->cmdq_vblank_cnt = 0;
> - mtk_drm_cmdq_pkt_destroy(mtk_crtc->cmdq_chan, data->pkt);
> + mtk_drm_cmdq_pkt_destroy(pkt);

Maybe mtk_drm_cmdq_pkt_destroy(data->pkt); , so you need not the local
variable pkt.

Regards,
Chun-Kuang.

> }
> #endif
>
> @@ -550,24 +553,24 @@ static void mtk_drm_crtc_update_config(struct mtk_drm_crtc *mtk_crtc,
> mtk_mutex_release(mtk_crtc->mutex);
> }
> #if IS_REACHABLE(CONFIG_MTK_CMDQ)
> - if (mtk_crtc->cmdq_chan) {
> - mbox_flush(mtk_crtc->cmdq_chan, 2000);
> + if (mtk_crtc->cmdq_client.chan) {
> + mbox_flush(mtk_crtc->cmdq_client.chan, 2000);
> cmdq_handle->cmd_buf_size = 0;
> cmdq_pkt_clear_event(cmdq_handle, mtk_crtc->cmdq_event);
> cmdq_pkt_wfe(cmdq_handle, mtk_crtc->cmdq_event, false);
> mtk_crtc_ddp_config(crtc, cmdq_handle);
> cmdq_pkt_finalize(cmdq_handle);
> - dma_sync_single_for_device(mtk_crtc->cmdq_chan->mbox->dev,
> - cmdq_handle->pa_base,
> - cmdq_handle->cmd_buf_size,
> - DMA_TO_DEVICE);
> + dma_sync_single_for_device(mtk_crtc->cmdq_client.chan->mbox->dev,
> + cmdq_handle->pa_base,
> + cmdq_handle->cmd_buf_size,
> + DMA_TO_DEVICE);
> /*
> * CMDQ command should execute in next vblank,
> * If it fail to execute in next 2 vblank, timeout happen.
> */
> mtk_crtc->cmdq_vblank_cnt = 2;
> - mbox_send_message(mtk_crtc->cmdq_chan, cmdq_handle);
> - mbox_client_txdone(mtk_crtc->cmdq_chan, 0);
> + mbox_send_message(mtk_crtc->cmdq_client.chan, cmdq_handle);
> + mbox_client_txdone(mtk_crtc->cmdq_client.chan, 0);
> }
> #endif
> mtk_crtc->config_updating = false;
> @@ -581,7 +584,7 @@ static void mtk_crtc_ddp_irq(void *data)
> struct mtk_drm_private *priv = crtc->dev->dev_private;
>
> #if IS_REACHABLE(CONFIG_MTK_CMDQ)
> - if (!priv->data->shadow_register && !mtk_crtc->cmdq_chan)
> + if (!priv->data->shadow_register && !mtk_crtc->cmdq_client.chan)
> mtk_crtc_ddp_config(crtc, NULL);
> else if (mtk_crtc->cmdq_vblank_cnt > 0 && --mtk_crtc->cmdq_vblank_cnt == 0)
> DRM_ERROR("mtk_crtc %d CMDQ execute command timeout!\n",
> @@ -924,20 +927,20 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
> mutex_init(&mtk_crtc->hw_lock);
>
> #if IS_REACHABLE(CONFIG_MTK_CMDQ)
> - mtk_crtc->cmdq_cl.dev = mtk_crtc->mmsys_dev;
> - mtk_crtc->cmdq_cl.tx_block = false;
> - mtk_crtc->cmdq_cl.knows_txdone = true;
> - mtk_crtc->cmdq_cl.rx_callback = ddp_cmdq_cb;
> - mtk_crtc->cmdq_chan =
> - mbox_request_channel(&mtk_crtc->cmdq_cl,
> - drm_crtc_index(&mtk_crtc->base));
> - if (IS_ERR(mtk_crtc->cmdq_chan)) {
> + mtk_crtc->cmdq_client.client.dev = mtk_crtc->mmsys_dev;
> + mtk_crtc->cmdq_client.client.tx_block = false;
> + mtk_crtc->cmdq_client.client.knows_txdone = true;
> + mtk_crtc->cmdq_client.client.rx_callback = ddp_cmdq_cb;
> + mtk_crtc->cmdq_client.chan =
> + mbox_request_channel(&mtk_crtc->cmdq_client.client,
> + drm_crtc_index(&mtk_crtc->base));
> + if (IS_ERR(mtk_crtc->cmdq_client.chan)) {
> dev_dbg(dev, "mtk_crtc %d failed to create mailbox client, writing register by CPU now\n",
> drm_crtc_index(&mtk_crtc->base));
> - mtk_crtc->cmdq_chan = NULL;
> + mtk_crtc->cmdq_client.chan = NULL;
> }
>
> - if (mtk_crtc->cmdq_chan) {
> + if (mtk_crtc->cmdq_client.chan) {
> ret = of_property_read_u32_index(priv->mutex_node,
> "mediatek,gce-events",
> drm_crtc_index(&mtk_crtc->base),
> @@ -945,17 +948,17 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
> if (ret) {
> dev_dbg(dev, "mtk_crtc %d failed to get mediatek,gce-events property\n",
> drm_crtc_index(&mtk_crtc->base));
> - mbox_free_channel(mtk_crtc->cmdq_chan);
> - mtk_crtc->cmdq_chan = NULL;
> + mbox_free_channel(mtk_crtc->cmdq_client.chan);
> + mtk_crtc->cmdq_client.chan = NULL;
> } else {
> - ret = mtk_drm_cmdq_pkt_create(mtk_crtc->cmdq_chan,
> - &mtk_crtc->cmdq_handle,
> - PAGE_SIZE);
> + ret = mtk_drm_cmdq_pkt_create(&mtk_crtc->cmdq_client,
> + &mtk_crtc->cmdq_handle,
> + PAGE_SIZE);
> if (ret) {
> dev_dbg(dev, "mtk_crtc %d failed to create cmdq packet\n",
> drm_crtc_index(&mtk_crtc->base));
> - mbox_free_channel(mtk_crtc->cmdq_chan);
> - mtk_crtc->cmdq_chan = NULL;
> + mbox_free_channel(mtk_crtc->cmdq_client.chan);
> + mtk_crtc->cmdq_client.chan = NULL;
> }
> }
> }
> --
> 2.18.0
>

Next message: Alexandre Ghiti: "[PATCH v2 01/10] riscv: Allow to dynamically define VA_BITS"
Previous message: Takashi Iwai: "Re: [PATCH] ALSA: rawmidi: Fix potential UAF from sequencer destruction"
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